Simplifying the volunteer owner discount system

Greetings, the Food Conspiracy Co-op is looking for some ideas on how to simplify a system for tracking volunteer owner discounts.  We offer discounts for owners who volunteer, contribute to our newsletter, participate in board meetings, etc.  We go through a process every month of and would like to get away from a cumbersome time consuming effort to a trackable easy solution.  Does anyone do a one time discount card system that owners present at the register or have other ideas?

Thanks for your consideration!

Kelly Watters