Hitting Shift will snap your rotation to the closes angle divided by your interval set at;
Options => Work Environment => Input Constraints and Guides => Incremental Angle
Thanks Ling !
I've been already using this method.. but I'm still wishing for a shortcut key that automatically rotates with the incremental angle. Similar to the Arrow+shift nudging shortcut, there could be an arrow + E for example to rotate clockwise or anticlockwise with that incremental angle. that would be more functional in my opinion !