How much are you charged for a click on your AdWords ad?
You’re charged $0.01 for every click.
You’re charged only the minimum amount needed to maintain your ad’s position.
You’re charged the full amount you bid.
You’re charged 10 cents more than the next highest bid.
Actual CPC is often less than max. CPC because with the AdWords auction, the most you’ll pay is what’s minimally required to hold your ad position and any ad formats shown with your ad, such as sitelinks. Keep in mind that your actual CPC may exceed your max. CPC if, for example, you’ve enabled Enhanced CPC or if you’ve set a bid adjustment.
Read more here: https://support.google.com/partners/answer/6297