You could tell them that you are very happy to pay them the price they printed on the menu and that they can present you with a payment terminal charging exactly that price, but that you will not do that job for them. Basically make the waiter select the 0% option.

But in the end you'll only annoy the waiter and not the owner of the restaurant who is actually running the tipping scam.

At least in that case you can safely select a 0 tip. It's worse when you pay up front and have to worry about a lower than expected tip resulting in some kind of retribution from the staff.