i'm using IDE 1.0.5
Why? Aren't there newer, better, easier-to-install cores for the tiny85 in newer versions?
There are internal oscillator calibration programs around, somewhere, that you can use to tune the internal oscillators, probably (I'm not sure that the Arduino cores will USE the resulting calibration, unless you add code manually.) Depending on how accurate you need the clock to be. Using up a third of your pins just to get a somewhat better clock seems painful.