I have found this thread to be very interesting. I have a different problem in my store.
I am trying to sell gift certificates (wonderful feature

) but would like anyone in the 5% club to not get a discount on the gift certificate, as this would potentially cause a double discount on a purchase. ie., Buy a gift certificate for 50 dollars, get a 5 percent discount, then purchase something with the gift certificate for $50 dollars and receive a 5 percent discount again.
Is there a way to limit the Group Discount to not be applied to a product, or am I thinking of this the wrong way?
Thanks.