@NWDD
I like the theory of nice round number you picked. When I first glanced at your add-on I scanned too fast and missed that one line where you are getting the ratio and attempting to get in-game time.
We can get to a few more nice round numbers "slightly less than five days." What if ZOS is using OS Ticks (864,000,000,000 in day)?
Then these three ratios also align for a Tamriel day?
--halja