UOM Decimal Rounding

I am setting values for material requirements in the routing of a revision. For the Required Qty field I was attempting to enter a value that goes out 10 decimal places. The UOM tied to this part is set to allow up to 8 decimal places to be rounded up. Will the system not accept anything beyond 9 digits for the decimals? My understanding is that if I had .0000000156 it would round it up to .00000002. Am I understanding this correctly? Looking to get a better understanding of how this works in E10.