NEW YORK — Starbucks will soon let customers leave tips with its mobile payment app, which raises a question: How often do people tip baristas?
The coffee chain says the mobile-tipping option will be available on its updated app for iPhones starting March 19.
The app has surged in popularity, with roughly one out of 10 purchases at Starbucks now made with a mobile device.
After paying with the app, customers will be able to leave a tip of 50 cents, $1, or $2 within two hours of the transaction at the 7,000 of the roughly 11,000 Starbucks in the United States that are company-owned.
But tipping can be a sensitive topic for customers, workers, and even Starbucks, which has faced lawsuits over how it divvies up the contents of tip jars. Some customers are happy to tip for friendly service, knowing baristas don’t earn that much. Others say they already fork over enough money.
Zee Lemke, 30, a Starbucks barista in Wisconsin for more than three years, said mobile tipping has the potential to boost the amount she earns. Still, she doesn’t like the idea of employers relying on tips to compensate workers. ‘‘It’s a way of claiming workers make more than you’re paying them,’’ she said.
Starbucks, meanwhile, has been pushing to get people to sign up for its mobile app and rewards program, which could help boost the number of times people visit its stores. The Seattle-based company says the mobile-tipping option is a response to demand from customers, many of whom no longer carry around much cash.
‘‘We asked our customers what they thought would be easiest and best,’’ said Adam Brotman, chief digital officer. There are no plans to bring the mobile-tipping option to stores licensed to other operators, however.
How Starbucks divides up the tip jars varies. Shannon Liss-Riordan, a Boston lawyer who represented workers in lawsuits saying shift supervisors should not share in tips, said the cash is typically distributed on a weekly basis.
‘‘They keep it in a safe and dole it out to employees . . . based on the number of hours worked,’’ she said.
As for the tips earned through mobile payments, Starbucks said they will be paid to workers in cash, in line with however they receive their regular tips.