That's not how you calculate age. Search this forum for it (Within the last 2 weeks I was reluctantly part of a very tedious thread where everyone tried to one up each other calculating it). Actually now that I think about it, if you wait long enough you won't have to search--I'm sure at least of those 2 pedants will find this thread and start trying to show their calculating prowess again by posting code in this one. And then someone will come along to correct them ad nasuem.
I'll only give you a general help: You don't solve this with rounding. You solve it by finding the difference in years (which you have done) and then finding out if their birth month and day has already occured in the current year.
I'm sure at least of those 2 pedants will find this thread and start trying to show their calculating prowess again by posting code in this one. And then someone will come along to correct them ad nasuem..