You will have to refer to specific questions for me to understand which ’rounding off’ you are referring to.
In general, rounding is irrelevant for the marks. Paper AFM is an exam that is testing your understanding, not your ability at simply applying rules. The marks are for your workings and for your assumptions (as in real life) and not for the final answer. There is rarely just one ‘correct’ answer for Paper AFM questions 🙂