Actually, the fact that money is calculated to the nearest one-hundreth of a cent is irrelevant
In Australia, they used to have a one cent AND a two cent coin, however when I was over there in 1995 they had gotten rid of both the one and two cent coins. Then, every transaction was rounded up or down to the nearest 5 cents. Trust me it was really nice to not have to carry around any pennies.
And as for having to re-program cash registers, well, here in Canada we went through that when the government introduced the country-wide sales tax known as the GST. Ya, it was a bit of a hassle (I was working at a drug store at the time) but in the end it's the cost of doing business. And, I'm sure in the the long run the cost of reprogramming will be outweighed by the savings of not not having to deal with pennies anymore.