The difference could cause a parachutist or bungie jumper to plummet into the ground, or the launching of a rocket to fail
The parachutist's calculations would suggest that he was going to arrive on the ground earlier than would actually be the case, in which case, he would release his parachute earlier. Using the rounded up figure builds in an additional safety margin.
The bungie jumper will only fall as far as the bungie will stretch. With the same mass but an increase in the value of "g" you get an apparent increase in weight. If the bungie is set for this heavier calculated weight, the lighter actual weight will make it stretch less and thus keep him further from the ground.
Similarly for the rocket, if the propulsion system is designed to meet the calculated values, it will more than cope with the actual.