How can I get my Attiny85 interupt to trigger
You main problem is that you have wired up your MCU wrong.

Pin 5 (PB0) is not the external interrupt pin. Pin 7 (PB2) is the external interrupt 0 (INT0) pin.

As a result your code will not do anything when the hall sensor changes because it is not looking at it.



I would suggest not trying to use the attachInterrupt() abstraction. Instead I would simply enable the external interrupt directly:

GIMSK |= _BV(INT0);


And use a proper ISR handler:

ISR(INT0_vect) {
    //Your ISR code here.
}