You are charged in the creator's currency. Prices are shown in yours for comparison.
Prices are displayed in your chosen currency so you can compare them, and the charge is made in the creator's currency.
Your bank may convert
If the creator's currency is not yours, your bank does the conversion and may add its own fee. That fee is your bank's, not ours, and it is why the amount on your statement can differ slightly from the total on screen.
Which currency you see
Set your display currency in your settings, or it is guessed from where you are. It affects what you see, never what a creator receives.
Creators
You set the currency you sell in and you are paid in it. Supporters see their own equivalent, and the exchange rates used for that are updated regularly.
The total is always shown before you pay
Whatever the currency, the exact amount that will be charged is on screen before you enter any payment details.