Do you owe a tip to the barista who poured your black coffee? New payment systems leave some in a quandary

Eli Gitelman uses the technology to check out and add a tip at a Dollop coffee shop in the Streeterville neighborhood in Chicago (860 N. Dewitt Place) on Thursday, Nov. 29, 2018. The story is about how technology is transforming tipping, perhaps most evident when people swipe their credit cards at coffee shops and are confronted with a tip screen prompting them to add a tip for a service they may not have considered tipping for before. (Jose M. Osorio/Chicago Tribune)

CHICAGO: Working the register at Dollop Coffee Co in the Loop one recent evening, Evelyn Rangel rang up a US$4.39 (RM18.14) almond croissant and stood by as her customer, having swiped her credit card, studied the tip screen that popped up. 

Did the service merit a US$1 (RM4) tip? US$2 (RM8)? US$3 (RM12)? Those were the options prominently displayed across the top of the Square payment touchscreen. Below there were additional buttons that gave the option of leaving a custom tip or "no tip" at all before signing to complete the purchase.