How much can we round off in exam

Hi John, Apologies if it sounds like a stupid question.But if in an npv question we get revenue of $4,774,500 that is 4.74 million can we round it off to 4775 as its been done in the past exam questions but it seems like too much rounding off millions but problem is if i dont round it then my NPV calculation gets real messy. Thanks, Furqan