Show Pre Calculated Shipping On Cart Page

I am developing a plugin which calculates the shipping of products and then adds them to the cart. It also calculates the shipping cost of the products.

I have added the products to the cart programatically but I am failing to add the shipping cost. It only shows Estimated shipping cost on the cart page.

I have set the shipping variables in cart variable but that is not working.

What would be the way to add the show shipping on the cart page? We have to add it programatically…


p.s : I was not being allowed to post in developers corner so, I posted here.