Yes. There are two ways to do it. The first way will automatically discount everything by a given %. The second way requires the user to visit some page on your site to activate the discount.

Method 1:
Use our quantity discount system to do it. You only need to enter one code into the system to take a % off everything.

Use this code:
.*~1=P.90

The above code means: for all partnumbers, in quantities of one or more, charge 90% of the price coded into the page. The power of method 1 is that your quantity discount can affect more than one item on your website.

new! For those of you that generate your website automatically, having a separate system for quantity discounts where the codes reside on other places than on the generated pages can be a problem. To facilitate that, we allow embedded quantity discount codes, which keeps all the data right on your webpage. Here are some examples.

Method 2:
You can add a tag to your cart display that will let shoppers turn on a "global" discount easily. Here is the code:

<a href="http://www.cartserver.com/sc/cart.cgi?item=b-2400^%3Ddiscount%3D^any+text^5">
Click here</a> to enable our limited time special 5% off discount.

Make it nice and bold as a promotion should be. Note that we had to replace the = character with %3D. This is to conform to URL encoding standards when talking to the cart via text link.

A more human readable version if POSTing to the cart is:

<form action=http://www.cartserver.com/sc/cart.cgi method=POST>
<input type=hidden name=item value="b-2400^=discount=^your discount^5">
<input type=submit value="Click to enable 5% discount">
</form>

The POST method is a lot of code to get into that one box in the config form, although it will go in if you get rid of the newline chars.

Yes. That way you can let THEM know that page URL where the discount button is but not tell the public at large. We have an example of that here

As you've surmised, one discount replaces another in the current revision of the shopping cart. We advise that you convert your gift to be "Negative Price" items, so you can have as many as you wish.

<input type=hidden name=item value="b-2400^=MX1=GC5^$5 Gift Certificate^-5.00^1">

You can use the =MX1= tag in to limit the qty to one.

We don't have a built-in system that will handle huge volumes of gift certificates, but here is a way to do gift certificates that works quite well.

a) SELL THE CERTIFICATE
Have a page on your site where you offer "gift certificates" for sale. Sell them just like you would any "intangible" item, typically marking it free shipping:

<input type=hidden name=item value="b-2400^=SF==TF=gc^Gift Certificate^op2^1">
<select name=op2>
<option>$5.00
<option>$10.00
<option>$15.00
<option>$20.00
...
</select>
Name of person(s) who will redeem<input type=text name=op1>

The shopper adds as many certificates as they wish, and checks out normally. Be sure to tell them that they will receive an email from you with their gift certificate number(s).

Note that the above code example assumes that you don't charge tax on gift certificates at the time of sale, but charge it at the time of redemption.

b) CREATING THE GIFT CERTIFICATE
At this point, you have an order with a gift certificate in it. You now assign a number to the gift certificate, a ten digit code, probably the first 8 digits of the order number, and the last two being anything from 01 to 99 depending on if they ordered more than one gift cert in the order. You could even use the first six, and have the next three be the amount (as a double check) and the last digit be 1 of x they ordered in that order.

You will need to keep track of these, so you can check them off as they are redeemed.

c) DELIVERING THE GIFT CERTIFICATE
Email the shopper with the gift certificate number, and redemption instructions along with other appropriate text. Instruct them to forward the message to the gift certificate recipient. If you do it that way, the burden is off of you to deliver the certificate to a shopper supplied email address that may or may not be correct. The shopper, being kept in the loop, also knows that the delivery has taken place, since it came through them.

d) REDEEMING THE GIFT CERTIFICATE
On your site, you will have a page where the recipient of the certificate can add the certificate number into the cart, where it will give them that amount off their order.

The code for doing that is basically our "flat" discount feature where a discount amount can be added to the cart. A twist on that is that we've set this certain way so only 10 digit discount codes are accepted. That cuts down on shoppers just entering something in and hoping for an amount off.

Here is some code you might want to use:

<input type=hidden name=item
value="b-2400^=giftcertflat=^Gift Certificate^op2^1">
Gift Certificate Code Number: <input type=text name=op1>
<select name=op2>
<option>$5.00
<option>$10.00
<option>$15.00
<option>$20.00
...
</select>

Note that the number MUST be in op1 for the check of ten digits to work. Also, the price must be in op2, even if op2 is coded as a hidden variable instead of something the shopper can change.

e) CREDITING THE GIFT CERTIFICATE
When you get an order in which someone has redeemed a certificate, the cost to the shopper is reduced by that amount, but will not go below zero. What you need to do now is to look up the number they put in and make sure it's in your system/ledger, and that it hasn't already been redeemed. You then mark it off as redeemed. It would be prudent to send a brief email to the shopper that originally bought the certificate telling them that it was redeemed, and by who. That way, if it was someone bogus, they would no doubt fuss about it.

SUMMARY:
The above system requires you to at least keep a file in a text editor containing the gift certificate numbers, the amount, the person buying, and the person supposedly receiving. There's room for fraud if you are not diligent (consider yourself warned), and it would be tedious to have more than ten or so of these per day.

We may make some improvements to the system in the future, but this is one way to do it that works right now. Obviously you can change some things in how it is suggested above, like getting the recipient's email address with the certificate and sending them a notice yourself.