MarketPress Transaction Complete Trigger Function

I have been working on integrating a custom freightquote shipping module into marketpress, all is going well thus far, however I have a question. When somebody clicks to confirm their transaction I need to trigger a function that will send a message to freightquote that confirms the shipping quote. I can write the code that is to be sent, I just need help figuring out where/how to trigger the function to run when somebody clicks to confirm their payment.

Are there any hooks or anything like that, that I could use that trigger when somebody clicks to confirm their payment?

Ryan