I have seen some games where two players are tied for VP at the end.
The rulebook states that the total of all resources for those tied players (Money, Science, Materials) will be the tiebreaker.
For Round 9 Upkeep, I have seen a lot of players on VASSAL not trouble themselves with the Materials & Science after paying their Money Upkeep.
I have been advocating that they do in fact produce their Materials and Science, even though they will not be able to spend it, because it could tip a tiebreaker, and so it is a tiny incentive to have more population cubes out on the map.
Am I correct on this?
Yes. You're supposed to complete round 9 upkeep the same as all the other rounds. I always try to do it unless the game is horribly lopsided such that the winner is painfully obvious. People are generally lazy though. Most don't do round 9 upkeep properly... most also rush to grab the discovery tile under the ancients instead of waiting for all combats to complete...