@paul this largely isn't about sales. I used to work at the Genius Bar and I cannot tell you how many times I was forced to turn down tips for helping people. $20 bills shoved into my hands, and I had to give them to a manager who just put them in the till and made a note. I don’t think it's unreasonable for the company to at least have it as an option for those who want to show appreciation for the free services and training that get offered at the stores.