Hi, I found this very useful bounding box size macro that works in fractional inches. However it has a bug. 

Can anyone figure out why it gives correct values sometimes and incorrect other times?

Example: 

I noticed 7/16 incorrectly shows as 3/8 with 4", 8", 10", 12" etc but correct with 1", 2", 3", 5", 6", 7", 9", 11" etc. 

Screenshot: 

4-7/16" incorrectly showing as 4 3/8"

5-7/16" correctly showing as 5 7/16"

Thank You.