Can a dimension style be associated with the symbol function for drilling?

Let me explain, I want to have my drill dimensions rounded to 64th of an inch by default and my smart dimension to 16th of an inch by default. Without changing the units in the document properties

and without going to change my precision in the property manager of the symbol for the drilling.

I also thought I could edit this in the text file Calloutformat.txt but I don't believe that by this path I can modify the units 

Could someone help  me

Thank you for your solutions