Some restaurant automatically include it in the bill, it's mostly up to you now a days to check over the bill before hitting accept

lunch is $18.49 and dinner is $27.99 add $2 on the weekends. Also it is not a buffet, it is a menu and you order the dishes you want off of it and they prepare it and bring. You can eat as much as you want of dishes on their all you can eat menu.

If it was on debit or credit all the machines have a tip option because they are restaurants the company who gives them the machine does it.