You don't often see them. I think there should be more rounds scored that way, but that's another matter. What fights featured rounds scored 10-8 by at least one judge without an official knockdown?
The judges gave Leonard a 10-8 round in round 5 (I think) during the rematch with Hearns. I think it was Shirley who also gave Leonard a 10-8 round in the 12th, which made it 112-112 on his card. 2 of the judges had Mayweather ahead 60-52 against Gatti after 6 rounds, so they must've given a 10-8 round for Mayweather after the 1st. Probably the 6th round.