sorry I should know this by now!!

What is the interbank rate??
The reason I ask is I wanted to know where to find the approx exchange rates you get on your credit card purchases (I know it depends on fees) - but I understood the exchange rate is still better than the normal tourist rates - is that right?? if so, where can I find what the current approx cc rates are??
(I am looking to pay up front for my
Disney Dining Plan on my credit card - and wanted an idea of what rate I would be getting, so I could decide whether to pay in advance now or hold out until I get there in Dec).
Many thanks
