Reliability of the Monthly E-mail Statement

I am wondering how “Interest on uninvested cash” is calculated in the monthly statement.

For example I earn interest both from USD and EUR and wonder how do they sum up at the end of the month. Is USD instantly converted to EUR during payout and then added to the historical return? Also is interest from share lending also being added up towards the total sum in the monthly statement.

Several times I have tried calculating it myself, with the .csv exports but there are always some sort of deviations and I don’t really know what to believe. I don’t have any problems with the statement itself, I just want to better audit my returns.

For example, for the whole month of May, I have earned 9,93€ and 12,80 USD which converted to the average rate for the month 0,918837 towards € is 11,84. On the contrary the exchange totals 11,80€ when each daily interest payment is calculated with the daily close. As you can see not a very big difference. What’s more is that I have not earned any interest from share lending. So, I am interested to know I have earned 21,77 but the monthly statement says 21,39.