Changing the quantity to 2 or more in the cart, admin gets the full price as com

When you add $2 product to your cart and go to payment the site will take $0.20 Tax and $0.20 Admin Fee, Vender gets $2.00 (Total is $2.40 but the payment amount is $2.20)

If you change the order quantity to 2 then the site will take $0.40 Tax and $2.40 Admin Fee, Vender gets $2.00 ?

If you remove both items from the cart the Daft order will say Vender gets $2.00 and Admin fee: -$2.00

How can i fix this? I have loaded 3 sites and all 3 have the same issue?

Thanks