Automatic Discount if Item (Membership) in Cart.

Hi,



Along with regular items that I sell, I also sell a “Diet Club Membership” which gives 10% off of the customers order total. I’m trying to find a way that if they buy the membership (in their cart during checkout), they will automatically get the 10% discount on their order.



Right now I ask them to enter a coupon code for the discount, but a good portion of the customers don’t enter the code or they enter the code and never purchase the Diet Club Membership. Then we have to manually refund or charge their credit card as needed.



Any help would be greatly appreciated!



Thanks,

Eric