A judge can score a round however he sees fit. That was the whole idea behind going from a rounds system to a points system, to differentiate between a guy winning a round and a guy winning it big. There was a movement back in the early to mid 90s, if my recollection is correct (it may have been late 80s to early 90s), to encourage judges to use the entire 10 point system. The ten point system, if I understand correctly, was a reaction to the 5 point system and the variance a 2 point round would create in scoring. That has never made sense to me, really, though I do recall a fight years ago with 5-1, and 5-2 rounds.
And then the Brits had a system where they used half points; 10-9.5, for example. That was only phased out 25 years (or so) ago, or less.