It seems like PayPal has changed a few things related to shipping for U.S accounts. Basically, we can't override any shipping rules you have configured in your PayPal Profile so you will need to remove those rules if you want us to calculate the shipping or you can simply
enable shipping in E-junkie without entering any shipping settings so that the shipping calculated by our cart will be 0 and PayPal will add the shipping to the order during checkout.
If you use our cart to calculate the shipping, then what you need can be achieved by following the steps given at
http://www.e-junkie.com/ej/help.shipping.php
Please see "If you want to use order amount based shipping" in that page.