Fix ecommerce site bug(repost)

One of my coders created these two sites for me using oscommerce: [login to view URL] [login to view URL] The shipping estimator gives a different price then the shopping cart page, which gives a different price than the checkout page. The coder I hired wasn't able to fix this problem. I want to fix this problem by making shipping costs the exact same throughout the customer checkout experience. Please note this fix needs to be applied to BOTH websites. Also, I want the checkout experience to be less pages. Right now the user has to push the continue button numerous times.. I want it to be a breeze just like [login to view URL]