163599 Add Feature to existing cart

Hi I have purchased a commercial shopping cart written in php and using a MySQL backend database. I need one additional feature added. The cart needs to have an extra field added to the database that will allow shopping points to be collected by site visitors when they make a purchase. The points can then be redeemed later on to get a free gift, depending on the number of points that they have collected. There needs to be an additional option added to the client login panel, as well as the admin panel to control these points. This new feature needs to be fully integrated into the shopping cart and the website. Thanks