Expense API currencyConversionRate discrepancy

Silvabox

We are getting some values with a currencyConversionRate from the API that don't line up.

For example, for an expense with:

amountInSubunits: 9994
currency: "R"
currencyConversionRate: 3.542376572335197
convertedAmountInSubunits: 35077
policyCurrency: "MX"

If we use the amountInSubunits and currencyConversionRate returned by the API 9994*3.542376572335197, the convertedAmountInSubunits should be 35403, NOT the 35077 returned by the API.

However, in another case for the same employee converting between the same currencies and same currencyConversionRate the values match the expected values.

Can someone help me understand why the convertedAmountInSubunits is not the product of the amountInSubunits*currencyConversionRate in some cases? Am I missing something?