In the US, it is a cost issue. Pennies cost too much to make and people tend to lose them.
I wish the US would get rid of the penny and nickel and go to a one decimal digit system instead of two. It would be better to go to 12 -> 1 just because of divisors (10: 1, 2, 5 or 12: 1, 2, 3, 4, 6). Much better for dividing food bills.
12 isn't the key divisor it's 60 - basis of the Babylonian system (hence minutes and seconds, and 360 degrees in a circle) and historically the basis of the 'old money' in the UK (as those of us who can remember it call it):
* pound - 240 old pence
* 10 bob note - 120 old pence
* crown - 60 old pence
* half crown - 30 old pence
* florin/2-bob bit - 24 old pence
* shilling/bob - 12 pence
* sixpence - 6 old pence
* thrupenny bit - 3 old pence
* penny, ha'penny (and before my time, farthing - one quarter of an old pence).
Missing intervals are the groat (4 old pence) in the old Scotch money.
