It's possible to apply a discount per user or user group. This is done in Extras > SimpleCart > Management on the User(Group) discounts tab.
This feature is particularly useful if you have a group of resellers or VIP customers that get a discount on the entire catalog. The discount can be either a fixed amount (per cart) or a percentage.
Click the right button to create a discount either for a user or user group, and fill in the modal. Use the field to search for a user or usergroup, and then set up the additional options as needed. The options are almost the same as for coupon codes.
User and user group discounts can only be applied if the user is logged in.