For every in-store purchase, a percentage goes to a charity of the buyer's choice (or one selected from a list). An option would be to get customers to vote which charities go on the list. More importantly, for each visit, the percentage for that customer goes up (limited with the 5th visit). For example: for first visit, the percentage would be .5% then for the fifth visit and those after, it would max at 2%. The customer(s) with the highest donations help present the check to the charity.