As far as I understand, the Korean mint stopped producing 1 and 5 won coins from 1995. Anything else older than that date is produced for mint sets and therefore rather uncommon. The face value of 1 and 5 won is about 1/10 and 1/2 of a US cent, which makes it useless really. If I am not mistaken, transactions are done to round them to the nearest 10 won.
