What do you say when you give $50 to a waitress and you want to tell her the money includes the tip and you don't want any change? I could say "I don't want any change", but it's not straight to the point and a bit confusing and unidiomatic. It's something a non-native English speaker might say, but what do native speakers say?
Let's say you are billed for $30 and you give $50, which means you are giving more than 15%, but you don't want change since you are giving $20 in tips.
I agree that "Keep the change" is the normal, idiomatic expression for this. The phrase is even defined in Wiktionary as:
an instruction to a taxi driver, waiter etc. to keep the change from the amount handed over as a tip
That said, I'd like to add that there are other ways a native speaker might convey the same sentiment. Sometimes I will give the waiter my money, and simply say, "I'm all set."
Other times I might say, "I don't need any change. Thank you."
Most waiters have been in the profession for some time and they've become pretty adept at reading signals from customers.
The idiomatic expression is "Keep the change."
That will be $30 please.
Here's $50. Keep the change.
Thank you very much sir.
