The cart layout typically has access to the product quantity and the product's unit price, depending on what your script captures. This covers most uses, but what if someone buys multiples of of the same item and you want to show the total price?
To do this, you can add the following to your cart layout.
In some scripts the price may be stored in product.opt.uv.
{{ (product.uv * product.qty)|format_currency(product.curr) }}