In coffeetime's thread on new coin series issued since 2000, he illustrates one such from Venezuela, containing a 12½c coin but no other denomination involving ½c. How is such a coin used in practice?
IME most of the time when a small denomination drops off the bottom of a range of coins, any higher denomination that requires the use of the dropped coin to give change is also dropped, or some other workaround is created. Two options are exemplified by the divergent policies of Denmark and Sweden in the 1980s/90s. At the start of the 1980s, both countries had coins of 5, 10, 25, 50 øre/öre. The smallest was more or less worthless, so was eventually ditched. This left the problem outlined above in respect of the 25 øre/öre. The Danes decided to do away with the 10 øre as well, leaving prices to be rounded to the nearest 25 øre. Fine. The Swedes kept the 10 öre but ditched the 25 öre, with prices being rounded to the nearest 10 öre. Also fine.
Now, in Venezuela it would work (albeit rather bizarrely) if the lowest denomination were 12½c -- all prices would be rounded to the nearest 12½c. but there exist 5, 2 and 1c coins as well, which presumably have some use. So: if my bill totals a sum of money ending in ½c that is not a multiple of 12½c, how do I pay it/how is change given?
(I believe the same situation may have existed in the Netherlands and its Caribbean colonies for a time as well. Wasn't the ½c abolished before the 2½c? South Africa today has the identical situation to the Netherlands, though the 2½c commemoratives are not intended to circulate. Back in Elizabeth I's reign in England, there was a period when no farthings were issued, but threefarthings and halfpenny coins were. But back then it was considered acceptable if you wanted a farthing to cut a penny into four, a solution that's generally frowned on these days.)