Again, What are you doing that requires time-keeping to the thousandth of a second?
Is it the fact that your outside-purchased timestamp creator appears to include milliseconds, so you feel compelled to include that in your calculations?
Were it me, I'd have to ask 'do I need to add an additional layer of complexity because it's really important to record that one document was posted one one-thousandth of a second before another?' There may be a reason, but I just can't envision it. They barely do that in the Olympics!
I'd ask you to take another look and see if you're being 'yanked around' by an outside product which, we're it examined, could probably be found to be grossly inaccurate.
I need that for Reporting. I need to develop a Business Objects report.