[radicaledward]

I thought of doing that, but our site is a bit unique in that we make extensive use of secondary groups for members. For example, my account has the following group memberships:

Administrators: 0% discount
Senior Members (been on the site for a long time): 5% discount
Friends of ACF (people that donated money to the site): 10% discount
Loyal member discount (registered on site for 365 days): 5% discount

Since the members were complaining about not getting all of the discounts this was judged to be the best course of action, as opposed to telling them that the highest discount is the total discount.