Earlier quoted context omitted.
There is a cost to handling cash too. Don't know how it compares to cards but with the latter you don't need to have fleets of armored trucks to move money around and robbers can only steal stock.
The cost is not so much about paying armored trucks, but most banks don't want to deal with small businesses that deal with cash.
Anything under 10 cents gets rounded down/up accordingly
It doesn't matter. Minting and transporting it, even in your pocket costs more than you'll ever get in dealing a more "precise" denomination