Sale order conditions less decimals problem

Hello Experts,

We want to use a condition for freight which is a proportionate on Gross value but the factor has many decimals but default decimal allowed is only 3.

E.G Gross value 1000000 the factor for freight is 0.00851 so the freight value should be 8510 but the value flows is 9000. How to deal with this.

If we increase the decimals it will lead to complications so we dont want to increase the decimals.

How else the problem could be addressed.

Regards,

G.Sethuraman