Terry Pratchett did a piece on this in his book, "making money".

A scam artist was asked to take over the capital city's rotten central bank, which contained the mint.

He made the point that these little coins cost more to make than they were worth, and what was the point? In this case they had a coin that was a tenth of a penny I think.

Turns out the point was when you didn't have a lot of money, these coins mattered. They could buy you a not so rotten apple core on the right street.

I think the point was; life is a lot different when you are poor, and that's when cents matter.