Surely there must be a law outlining how rounding of sums will be done, rather than leaving it to the store owner's discretion? (Here in Norway, we've gotten r

Surely there must be a law outlining how rounding of sums will be done, rather than leaving it to the store owner's discretion? (Here in Norway, we've gotten rid of the 5, 10, 25 and 50 øre (cents, if you like) coins since I was a kid; the smallest denominations coin now in use is the 1 krone. Stores round like any mathematically inclined would -.01-.49 sums are rounded down, .50-.99 sums rounded up.