Yes, well... Funny story, but a slightly mentally unstable guy in Queensland insisted on paying for a bag of mushrooms at his local supermarket mushroom by mushroom. They disallowed it, so he left and entered the store 40 times.

The reason? The scales weren't terribly accurate and rounded down. Each mushroom came to 0.48 cents, which because they rounded down came to nothing. He got a bag of free mushrooms. And a lifetime ban from the store.