Suggestion: System has the provision to record the daily exchange rate for currency which can be used in transactions. Daily exchange rate menu exists in Finance-> Finance settings-> Masters ->Daily exchange rate.
Users can add the daily exchange rate of currencies like USD for a date and select currency code from as United States Dollars. To currency is default indian rupee. Users have to select the date range for the exchange to be active. Then users need to enter the exchange rate, sell, buy to finish the record.
Please refer the screenshot below.Daily exchange rate.png