Is there a way to change the set modifier for rotating objects?

[BranBrandon]

I'm talking about the shift + rotate = (0º, 45º, 90º). It's come up enough that I figured it was worth asking. I've checked for settings, but I could be overlooking it

[spinhead]

I don't think so. I type in exact degrees of rotation; it helps if you can do division in your head quickly . . .