Note these aren't games I play much, but I think the general rule is to have 300 big bets in your bankroll for the game you're playing?
That being the case yeah you're probably rolled for 5/10c and you wouldn't move up to 10/25c until you had at least $75 in your roll.
It's all about your level of comfort and how swingy your game is though. If you're a loose player or you're prone to big swings you'll want more in your bankroll.
Shouldn't make any difference if you're playing Stud8, BTW.