Replace change with lotteries

Stores should have the option of using lotteries to replace giving change to cash paying customers. Say your bill comes to $10.45 and you pay with a $20. Normally you would get $9.55 in change. But a lottery using store would instead give you $9 and a 45% chance of winning an extra $1. The store's cash register would quickly determine if you won. On average customers and stores would break even with lotteries. But lotteries would save everyone a bit of time and save stores and customers from having to carry around change.