Do you lose people from your shopping cart?

A recent PayPal email newsletter states: "Did you know that about 50% of online shopping carts are abandoned at checkout? (Source: Shop.org/Forrester, 2007) This means a large proportion of customers shopping in your online store never finish their purchases." PayPal is intent on selling their express checkout system, but can I suggest that an equally important reason why so many orders fail at this stage. This is that the seller has missed or given unclear information on their main site as to what freight and packing charges may be. Too often I have had to go into a site's shopping cart to check just what the total payment will be. Then I cancel out even though I may intend to go back and order later. The worst kind of shopping cart is the kind that insists on personal details before it will offer the answer to the really important question: How much is this going to ccost me? I have asked about this at several computer forums and have had confirmed that this is a major reason for dropping out of the shopping cart.