OSCommerce Job - Add ability to use coupons to existing cart

I have an already existing site that is using the OSCommerce shopping cart. I need the ability to use coupons. The customer on the website will need to be able to enter a coupon code. When that code is entered, the product will receive a discount. The discount must be reflected in the order total. The coupons must be able to be added using the existing ADMIN panel in oscommerce. The coupons must be able to be used multiple times. ************************* There are a few contributions available for using Coupons on the OSCOMMERCE website. However, if you intended to use one of them, you would have to enter the codes manually. The reason is, there have already been several modifications made to the cart using a few contributions. So this is not as simple as copy and pasting files. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). **The customer/buyer of the website needs to be able to enter a coupon code during the checkout, so they can receive a discount on the items they are purchasing. A % discount would be fine. Also please be careful not to mess up any of the existing modifications of the cart.** ## Platform PHP,Internet Explorer, Firefox