A true tie (assuming infinite measurement accuracy, which is perhaps what WMB was talking about) would be exceedingly rare.
But, it really doesn't matter, since when the fans or coaches say "the tie goes to the runner" what they really mean is all close plays should be given to "our" runner. They don't really mean a literal tie - they just mean too close for THEM to see a clear out, and since they are on the offensive side, that doesn't have to be very close at all.
