I wonder what would happen if I refuse to interact with the terminal and ask the cashier to read it to me. Would they select a tip without asking? Would they be

I wonder what would happen if I refuse to interact with the terminal and ask the cashier to read it to me. Would they select a tip without asking? Would they be too embarrassed to ask me for a tip to my face? Feels like punishing the wrong person, but it would be still interesting to test.