3 digits after decimal point

Dear all,

As the price for one of the commodities for a buyer has been now settled in 3 digits after the decimal point, we need to create an option for entering 3 digits after the decimal point in the commercial invoice.

I understand that I cant just go and change the settings in the transaction OY04.

Is there any other way we achieve this.

Please Guide me..

Regards..!

Andy