Hi,
The products in the cart are sorted like that: The latest product added is the first one, the first product added is the latest one.
I think that it's how most of the shopping carts handle that.
It would be possible to sort the products the same way as listing by changing the line:
$query='SELECT b.*,c.* FROM '.hikashop_table('cart_product').' AS b LEFT JOIN '.hikashop_table('product').' AS c ON b.product_id=c.product_id WHERE '.implode(' AND ',$filters).' ORDER BY c.product_parent_id ASC,b.cart_product_modified ASC';
in the file administrator/components/com_hikashop/classes/cart.php but since it's a modification to the core of HikaShop, you will loose it when you update.
For example, to sort by product name, you could use that instead:
$query='SELECT b.*,c.* FROM '.hikashop_table('cart_product').' AS b LEFT JOIN '.hikashop_table('product').' AS c ON b.product_id=c.product_id WHERE '.implode(' AND ',$filters).' ORDER BY c.product_parent_id ASC,c.product_name ASC';