Every listing is in one and only one currency. You are required to pay the full amount in that currency to the seller. That is the actual price. There is no invoicing in other currencies.
eBay's payment processor will convert your USD to the currency required at it's "buy rate" (which is about 3.5% higher than the "mid-market rate" that eBay uses to post an "approximate" conversion to USD under, or on some pages instead of, the actual price). With some payment methods you might get an option to have someone else do the conversion (e.g. your bank), which might be at a better rate.
