I want to set a fixed pricing price PER CART instead of per product. Is this possible? Please guide me how.
I'm using Magento 18.104.22.168 (1.9.x), community edition.
I'm pretty sure you don't actually want it, because it sounds like you want to put a square peg into a round hole. With sufficient amount of force everything is possible, just it's not the right thing to do. I suggest you explain what do you want to achieve first. For example right now I have a feeling that you want to sell some kind of bundles.
Check out Extra Fee Extension it will allow you to add fixed or percentage extra charge in shipping area & It will be added to shipping amount for the cart.