[Musiclab]

To the OP, are you hearing the vocal as being out of tune? Or are you looking at it on a grid? A few observations of mine have been this, when I used to use AT if I was in a hurry and I used the auto mode I would find that there would be notes sharp.
But more importantly there is no perfectly in tune vocal that sounds like a human being sang it, sliding into a note, vibrato, they're used for interpretation, take away all of the modulation and really you're better off getting vocoder.