Well, I have been very happy with my Hotwire results, but you peaked my curiosity. So, I went to Hotwire to confirm, or not, their policy that states that you will know the total cost before you purchase. Below is what I found:

>>The airfare quote we show you is the final price for round-trip travel (per person in U.S. dollars). Period.

With hotel reservations and rental cars, the Search Results page will show the base price. On the next page -- before you make any commitment to buy -- you will see the total price including all taxes and fees. You will always know the total amount you're paying before you agree to make a purchase.<<

However, you may want to contact Hotwire customer service just to make sure.

John