Tally EEFC a/c. with rupee a/c.

Hello friends we have an EEFC A/c. where transactions are done in $ Account, also we use to transfer $ to current account, I want to know which method are adopted to tally EEFC a/c. with Rupee which conversion rate are taken for an ERD entries. Please provide an appropriate example to understand the better method adopted in this case.