Physics doesn't really mark for sig figs (as far as I've seen in the marking guidelines for the past few years), however, from what I've heard, sig figs are a 'Band 6 indicator' which just means its a mark of a strong student that they're aware of the accuracy of their calculations. And answering the question above, Yes, any calculations involving gravity are technically inherently accurate to 2s.f. since the value you use is 9.8 (2.s.f) on the data sheet.