418371 penny auction 2

we have a penny auction script in place and running. its a snabid clone. right now we have it set up where the timer adds time every time someone places a bid on the auction. what we are looking for is to have a cap on how high the timer will go up. We have the timers running for say 3 hours then when it gets down to the last few seconds two people bid back and forth and the timer will just keep adding time in upwards of another 2 hours. We would like to cap it so it will only be able to add time up to 5 min. regardless of how many bids are placed, and continue to count down from there.