The coffeshop in the bookstore picks a “Customer of the Week” who gets five free drinks. Which—if this plan were publicized, which it isn’t—would be a very good incentive for being nice to your barista.
I would never get it, though. Unfortunately, in my six years working in the candy shop, we weren’t even allowed to put out a tip jar. I have never gotten past that to recognize that counter service might deserve a tip (and to be honest, counter workers do get minimum wage, unlike table servers).