Field help (STAAMT1) 

The statistical value of the goods is calculated by applying the fiscal value (without the invoicing elements, including those integrating the fiscal value), the EU increase coefficient defined in the ship-to customer record or supplier, then, by adding the invoicing elements when their setup is aimed at being a part of the fiscal/statistical value calculation.
This value is converted into the company's currency (instead of the journal's currency) using the rate type defined by the setup of the TC chapter, CDF group: EECTYPCUR - EU currency rate type, and the rate at the date of the journal.