Usercart X Standard has a very comprehensive Discount Code System. You can discount individual items, all products, catagories of products or even set individual pricing discounts for your favourite customers, or a wholesale rate. Discount code can be set for single use or multiple usuages. They can be as little as 3 characters long or as long as 144 characters long. They can include numbers or symbols. Discount codes are a great way to attract new customers and retain existing customers.
It feels good to get money off. Even better when it's from somewhere you have done business with before and trust.