Tipper

Tipper app will help you to calculate how much tip you need to pay for the percentage you prefer. All you need is to enter your bill amount, then look up the shown percentage amount.

You will be shown a set of most common percentage values, and will be allowed to select your customer percentage value to enable you."

App will also show you what the total amount you should be paying, this will be the bill amount + tip you should be paying.