Inquiry about rounding product prices in other currencies

Version 3.0.3.8
The default currency is the dollar, and the secondary currency is the euro.
Other currency prices (euros) are displayed in the store interface with decimal places.

I want to approximate the prices in the secondary currency to be like this, for example:
Product price in dollars is 30 $ , but according to the exchange rate, it becomes 28.34 €
I want to adjust the price in euros to be 28.90 € (meaning I want to adjust all product prices in the store so that there are no random decimal places for the secondary currency).

In which files should this modification be made, and how? so that it does not conflict with payment gateways like PayPal and others.

I tried modifying the currency.php file and the prices appeared as I wanted, but during payment these numbers are not used, but rather the actual numbers are fetched.

You may need to edit the payment extension as well. Certainly for the PayPal Checkout Integration extension.