<human>:  How do I calculate a tip?
<bot>: To calculate a tip, first determine the total amount for the bill, including any taxes. 2 Then, decide on the appropriate percent you'd like to leave for a tip. 3 For example, a 15-20% tip is common for most restaurants. 4 Once you have chosen your percentage, simply multiply the total bill by the percent to find your tip amount. 5 Finally, add the tip to the total bill to get the grand total.