[Ginkasa]

I think it depends on how you define "ending." As for the actual final string of cutscenes that lead into the credits... There's only three. And those are pretty darn similar. They end in the same place. If you have enough "Effective Military Strength" and choose the right option you can get an extra little bit right before the credits, but that's it.

If you're referring to everything leading up to "the decision" (which then triggers the "we're coming up on the credits" cutscene), then there are several variations depending on what your EMS is. Again, nothing terribly drastic. It all ends up in the same spot.

Also, there's a small coda at the end of the credits. Supposedly it only appears if you finish ME3 with an import from ME2 or as NG+, but I had an import so I don't know.