Of course not. Your vote is already destined not to change the course of the campaign. As far as deciding the course of history, your vote is worthless.
"But if you don't vote for Rubio, Rubio won't be elected and Trump will. The horror! You'll be throwing your vote away!"
But if YOU don't vote Cruz, Cruz won't win either. In general, if not enough vote for candidate x, candidate x won't win. Why aren't you--the Rubio supporter--throwing your vote away? If you (y'all) vote for Cruz, Cruz would win!
I never got into philosophy to be liked or to be popular. Whoever gets into philosophy to be on the winning team never gets into philosophy. Philosophy is a failure. Philosophy chooses first place or no place at all; and sometimes it is said that the first shall be last. But there is no fear in failing when one fails with honor. Socrates chooses to be an Olympic hero and failing that, death.
You can be a sheep. Sheep are stronger in number. The world needs sheep. Democracies need sheep. But the world also needs shepherds. And sometimes it even needs a few more wolves.