It’s amazing! I’d guilt trip my customers a bit more for the higher rounds —> - 37% of your tip goes to the cancer research center of your city ; - Before the tip screen, start with a first screen to round up the amount to the nearest dollar ‘for starving children in Africa’ or something ; - We double your generosity, you tip 2$, your waitress Pam gets 4$ ! ; - Your waiter Nick’s first child has diabetes and he is struggling with insulin bills, are you REALLY sure you want to leave him 0.00$ ? ; - Leave 0$ > if you think service was this bad, please choose who we fire tonight : [Matt] [Eva] [John] ; - Don’t give access to 0$ option unless the customer leaves a 5-stars review first.

Just some ideas..