I am trying to design a tank in SI units and I specified the roof thickness as 0.5 cm. However, in the output, thickness is still based on British units as seen below. Which gives a roof weight less than the actual. Is there a way to get plate thickness with 1 mm increament instead of Britich system? (In my case it is 3/16.)

TANK - Roof Design/Analysis Data
API-650 11th Edition, June 2007

SUPPORTED CONE ROOF Structural Library: GERM91.BIN
Roof thickness per 5.10.2.2, Cone Roof (cm. ): 0.47625