Using the cashierless payment feature may charge you again and again. My self-checkout experience has usually had glitches with my payment / credit card which work perfectly fine with the cashiers. What caused the extra billing was that the machine goes red and makes a "whomp-whomp" sound to indicate payment did not go through so I try again and again until I gave up on the self-checkout terminal and proceeded to check out with the cashier. Problem is that I was charged 3 extra times!