People don't generally round their ages, and especially not in that kind of situation. They might miss it by a year (I always have to stop and figure out if I'm 48 or 49 and will until about three months before my next birthday ;-), but rounding would come in things like "tell me your knees don't creak when *you're* in your fifties" or something like that. Given, too, that he was trying to impress upon her just how their 'god' had been cheating them, if anything he'd've rounded *up*. But this is Jack and at the heart of it, he's going to say it like it is.