SAP Exchange Rate Calculation Issue-Document currency to amount in LC

Hi Experts,

I  am facing issue in exchange rate scenario .Amount in document currency is not matching up with amount in Local currency .There is amount discrepancy by fraction of decimals . This is probably because of rounding .

Scenario details are as below.

1. Sales Order created dated 27.07.2015.
2. Document currency is in USD for Sales Order. Company Code default currency is MYR.
3. Exchange rate as on 27.07.2015 is 1 USD= 3.60 MYR.
4. Delivery was created with reference to sales order on 27.7.2015, followed by invoice .
5. I noticed SAP is not calculating Tax correctly.
6. Amount in Local currency also does not match when evaluating conversion from USD to MYR in FB03 .
7. I  have attached the calculation in Excel .

Appriciate everone's time .

Regards,

Santosh