I am not sure if this is the right place for this but here it goes.

I am using 1.3.9h and want to add the option for tracking at the shopping cart/checkout before payment, so that it adds the total to the order being bought.

All items are going to have free shipping, but I want a customer to be able to buy an item for lets say $1.50 and have the option not to have tracking by default or to add tracking for lets say $1.25 to their order.

I also want to set it up so that if a customer's order is lets say, $20.00 or more, then tracking is added automatically and is free.

I know how to add it as an option for the product, but I want the customer to add it on the complete order instead on each individual product.

Any help on this matter is appreciated since I've been looking around for an answer to this problem for some time and everything I've found has been irrelevant. Thank you.