Tipping is a tricky business. Between waiters and cab drivers and barbers, all that extra money can add up. And it doesn't make things any easier that each service tends to have its own guidelines for how much to leave on top of the bill.
Mobile credit card reader Square dug into its user data - that's millions of dollars of payments processed through hundreds of thousands of transactions - to find out how people in 10 big cities across the U.S. treat the tipping dilemma. The company collected data during the month of January from any seller who had the tipping feature of the device turned on, from a restaurant to a hair salon.
According to the data, Chicagoans were the most likely to leave a tip, while Denver residents left the biggest tips overall, coming close to 17%. Customers in Atlanta and Tampa were the least likely to tip, and San Franciscans left the smallest tips, only 15.5% on average.
Here's how the rest of the cities shook out.