Possible, for sure. But if votes are being altered, there's probably an equally valid chance votes are being conjured out of nothing... maybe even in the names of people who didn't show up to vote at all.
If you are going to participate, it does make sense to me to vote third party or write in yourself or possibly "no rulers" as @lukestokes has now suggested... primarily (for now, anyway) just to give other fellow humans confidence that there are, in fact, a large number of dissatisfied populace who no longer wish to settle for the lesser of two evils, and who are dissatisfied enough that they won't when it comes time to actually vote.
RE: A mathematical explanation how voting third party in 2016 is the only vote that counts