How can I get a total on my payment section?

Is there a way for customers to select items on my form that would automatically put an amount due on the payment section? For example if my customers decided the want a one way airport shuttle trip, it would be $43 each or if the decided they need to book a round trip it would be $73 each. 

Yes, this is possible by adding a Form Calculation on your form. Here's a guide on How to Perform Form Calculation Using a Widget.

Then, you can pass the total amount to the Payment Field. Please refer to this guide: How to Pass a Calculation to a Payment Field.

Let us know if you need further assistance.
Regards.