No, not every time. I was able to upload normal times before I achieved the 0s. And after that on 2nd level I uploaded a normal time before the 10s came.
About the real times, both of them would have been 1st place. Also if I remember correctly, the 0s made the best and last times incorrect, they were displaying about 0s. But in the 10s time the last and best times were showing the actual correct time of about 25s, even though time of 10s was uploaded.
On unrelated note, I just noticed that the time pauses when te Hi-Scores are open, but gravity still takes effect. So opening it before taking a big fall can save you quite a bit of time :P