Track the order value when a customer click a adword ad and purchase

Hi

Is it possible to get the exact amount from a purchase/order which have been made after clicking a customer have clicked a Google Adwords ad? Or store the ordernumber for manual check?

The reason for me to do this is to evaluate if it is worth all money I am spending on adwords.

All orders have different order values so I cant set a fixed value in Google tag manager which I’ve installed.

Is there a way doing this? By hand or via a plugin?

Thanks in advance.