Will I go to jail for my first DUI with a .131 on my breathalyzer test?

My boyfriend was stopped for speeding in his friend's car. He was asked to take a breathalyzer test, and his final result was a .131, He was taken in, finger printed, and I picked him up immediately after that was done. Now, although this is his first DUI offense, he does have a background. He did six years in prison for statutory rape. And he also was in Drug and Alcohol a few years ago ordered by his probation terms. I assume it was because he needed anger management? I'm not sure. But anyways, This would be his first DUI offense. So with all that said, is it possible he will do jail time? Does it matter if you have a criminal background even if it has nothing to do with what your charged with? He's pretty positive that the worst his sentencing will be is a weekend in prison, and classes. What do you think?