In the lawyer's case one might argue that it's just a time quantization inaccuracy. There's no smaller unit of time than an hour for them.

One can argue that there should be, but billing in 10 second increments might also be a bit much to ask.

One would hope that they would at least aggregate multiple smaller-than-resolution time blocks into one before billing though. (Five documents over the course of a week ends up costing the same)