We use the currency exchange rate on the import date from an open API Yahoo Finance. You can check the current exchange rate with a currency converter.
If the currency of your ad service and the currency of your Google Analytics view match, then the costs are uploaded without any conversions.
If the currencies are different, the costs are converted to the currency of your GA view using the Open Exchange Rates API.
Note:The conversion from Yandex units to a Google Analytics view currency is described in this article.