At VX, we're 125% over 80 hrs.
Suppose you get awarded a 80 hr line. You pick up a 2 day trip worth 10 hrs. Your pay would be 92.5 hrs for the month, 80 original line, 10 new trip, and 2.5 incentive pay which in this case is 10 hrs * .25 = 2.5 hrs
If they get desperate with low reserves, theyll send an email for premium pay on a trip on whatever dates they publish. That premium goes above the guarantee. Premium is 125% and if I recall correctly you double dip above 80 hrs.