Quite a number of countries, no longer have any fractional currency at all. The basic monetary unit is the lowest level of rounding, and even though they are officially on the decimal system, there is no coin smaller than the statutory unit – peso, yen, franc, whatever.
In the USA, before WWII, when the penny-cent was the smallest coin in circulation, it had the purchasing power now enjoyed by about 20 cents. So the US could abolish the pennies, nickels and dimes, and round everything to the nearest quarter, and introduce coins for $1, $5, $10 and the utility of pocket change would mirror that of 75 years ago.
WalMart already rounds everything off to the nearest dollar, expressed as X.88.