My wife and i own a contemporary pottery studio that offers what we call pottery perks program. Where in we offer a 20 gift certificate for every six times a person reaches a $20.00 limit. Having a lot of customers and keeping our little pottery perks information cards are starting to pile up my counter space here. I have started a layout for putting such information we acquire, per person, in the fields of: Name, Email address and Birth date. with each entry int this program / data base I could add a new contacts info or update one. The $20.00 dollar level per six times I understand is a simple equation like something maybe excel would use. If I could get some pointers this would help me out tremendously.
I have included a screen capture of what I have so far.