Those extra two rounds are called the champion rounds, added to see which fighter has that extra desire and skills to take the match from the other guy. Who have the champion heart, as it were.
A good judge (three, including referee) will take into consideration how many potential blows are blocked or deflected, as well as the ones that get by.
Pro boxing is one of the most dishonest and dirty sports around, and has been for probably the beginning of time.. But I still love boxing, one of the more electrifying sports, when a good match is involved. Attending an excellent fight is something to remember always.