Part 1

1. pick any unit (I tend to use manuf unit)
2. add new DB column for storing decimal numbers with 4 digit after comman precision
3. add matching:
   • field declaration to the unit config
   • grid column declaration to the unit config
4. create record in DB with 145.575 value

Part 2

1. put needed value in format field option in unit config
2. confirm, that 145.58 value is displayed in grid

Feel free to use any format you like that has digit and f letter at the end.