The shop will. It can be a lot of money in aggregate. It also creates really pathological purchasing incentives, where spreading out large purchases over several small purchases can yield significant savings for the purchaser.
There's one exceedingly simple answer:
Keep the penny (possibly a new one that is cheaper to make).
We're basically breaking into jail on this one, creating more problems than we're solving.
The other direction avoids a lot of stupid complains. Nobody will complain if the shop gives them a $0.04 gift.
The shop will. It can be a lot of money in aggregate. It also creates really pathological purchasing incentives, where spreading out large purchases over several small purchases can yield significant savings for the purchaser.
There's one exceedingly simple answer:
Keep the penny (possibly a new one that is cheaper to make).
We're basically breaking into jail on this one, creating more problems than we're solving.