I suspect it's different in different states, depending on overall traffic volume and other factors. In some states, such as New Jersey, you don't have to remain at a red light until it turns green. There, for example, it's perfectly legal to roll through the light while still red once you've checked to ensure that no traffic is approaching.

Problem is, a lot of cops don't even know the complete rulebook as it pertains to cyclists, so you're taking a risk that you'll get hassled anywhere if you don't come to a complete stop.