Thank you! I have done the above...

However, wanted to ask you. for rounding factor for currency they are read only. 

I cant edit the rounding factors for the currency ... though the Technical database worked. 

any resolution for the currency. as they still show rounding factor 2 in the currency setting after changing the Technical. 

Access the Decimal Accuracy Settings, under Technical Menu.  Look for the entry related to pricing. Just edit this entry and set the precision to 3. Also you can  Update Decimal Precision for Currencies,  open the currency you are using (e.g., USD, EUR) and set the rounding factor to 0.001 (which corresponds to 3 decimal places).

Then check and update the entries

• Ensure that the purchase order  and invoice reflect the new decimal precision.
• Create a new PO and check if it accepts prices with three decimals.
• Create an invoice and verify if it matches the supplier invoice with the updated precision.