If the previous 100 hour was overflown but not for hire, is the time still subtracted from the next 100 hour?
According to FAR 91.409 b, the 100 hours can be overflown by ten hours in order to fly the plane to a place where the inspection can be performed, but this time must be included in the next 100 hour period.

If the five hours over the designated 100 hour time limit was for hire (ie not flying the airplane to somewhere the inspection could be performed) then they were technically illegal. And no, that wouldn't change the fact that you must count those hours in the current 100 hour cycle.