I'll add to Tom's comment. Rather than take the whole cut at once, reduce your depth of cut and do a few small cuts. They will be cleaner and you can control your round-over much more easily thus preventing the problem you're having.
That's one of the problems with routers. There's a variety of ways to address a problem. Not one is particularly better than the other, just a different approach to the same problem.
My first take would be use a router table and fence with feather boards. Failing that, I'd use shiis with an edge-treatment bit, if your workpiece is wide enough. If not, I'd use a foot.