What is the value in “Qty. per Unit of Measure” for this case ? What is your Base Unit of Measure, is it PC, if it is PC, then “Qty. per Unit of Measure” should be either 0.005 or its reciprocal 200, check it for yourself?

If it is PC, then in this particular case the calculation is simple and I believe it must show what you are expecting.

For your earlier example, the value I suggested will work.

Recently, there was a discussion on this website on this topic and people suggested to use smallest unit as Base UoM and to avoid decimal places, search that discussion for yourself.

Suppose I store the value 3.3333 in the “Qty. per Unit of Measure” field.Which is actually comes from 10/3. But this value 3.3333, multiply by 3 will never gives me 10.