DEAR MISS MANNERS: I was taught to tip generously, and I don’t mind tipping people who provide direct services: restaurant waitstaff, bellhops, spa workers, hairstylists, nail salon workers, hotel housekeepers, etc. However, I am confused about all the tipping requests I am presented with now. For example, if I buy a hot chocolate or tea at the coffee shop, they’re just pouring a premixed substance into a cup and handing it to me. Is that really a service? When I picked up a takeout order recently, the credit card machine suggested a minimum 15% tip. I gave 10%. The cashier looked disgusted. W…