Question

What percentage of the bill amount should you leave as a tip for a waiter at a dine-in restaurant

Answer 1

Depends on their service, and how kind you feel. Haha.

In all realness, the usual percentage of tip you leave is 10%, meaning you were not all the way satisfied with your waiter/waitress.
Or 15% meaning they were pure excellent.

Hope this helps!

Answer 2

The average would be 15% of the original costs of the bill should be a added as a tip