Transferring between base and foreign currency accounts

Transferring between base and foreign currency accounts

I find it impossible to get the exchange rate correct to let inter account transfers balance. 

There is not enough digits allowed when entering the actual rate at which the conversion was done. 

Can you please create a feature that will allow you to enter the base amount and forex amount and then automatically calculate the exchange rate received when transferring between accounts. 

There is always some balancing transaction needed to try balance the books. It makes no sense. Please help