R12.1.3 - Rounding of AR Invoice total when invoice currency is different than functional currency

We have an OU where functional currency is CLP (Chile Peso). An AR Invoice is entered with the following details. Line 1 Amount is $400, Line 2 Amount is $100. Exchange rate is 1 USD = 492.070287319841 CLP. When we click on the details button of the AR Invoice and use the functional currency invoice total is 246034 CLP, whereas the value by converting using exchange rate is 246035.14365992. We want to know why this discrepancy in the expected and actual value?