The cart has the following discounting capability:

1. Product Level Discounts
2. Price CLass Discounts
3. Category Level Discounts
4. Order Level Discounts By Role
5. Member/DIstributer Pricing
6. Member Pricing By Role
7. Member Discounts By Role

Please see page 74 of the users guide http://www.smith-consulting.com/Portals/0/docs/smithshoppingcartmanual.pdf for more info.

Currently the cart doesnt support discounting a percentage based on the order total $ over a certain amount.