This. I think it's built-into the newer technology POS systems. The little cafe in our office building just got a new one with a tablet type thing that you sign with your finger and has a tip screen. The only people who work there own the place and I've gotten to know them and don't think they did it to milk the customers. It's just an integrated part of the new system.
It's the same screen I see on all those same type POSs and on small shops or delivery places that use Square for iPhone