Product/ Checkout customisation

I have tried multiple ways to customise the product/checkout to display a clear breakdown of the cost and calculate the below in the cart/order summary.

Standard product purchase price: £

Compulsory transfer fee: £80.00

VAT to be added (if applicable)

Subtotal:

I would appreciate some support

https://regdealers-com.myshopify.com/

Thanks for your help, however it is not calculating the amount into the sub total. I also don’t have access to the checkout.liquid and/or checkout-template.liquid file which makes it more difficult

Hi Thanks again for your support but I want the breakdown to look like this

Standard product purchase price: £

Compulsory transfer fee: £80.00

VAT to be added (if applicable)

Subtotal:

Thanks again but it is not calculating the £80 DVLA and not showing up in the checkout summary. As mentioned before I don’t have access to the cart.liquid and only main-cart- Items .liquid.

There is no subtotal mentioned in the"main-cart-item.liquid"

Thanks for your response but this is now working or displaying anything