Your idea gave made me think about what I was doing. To use a "house wiring" analogy, I was abandoning the existing wiring for "getShipping()" in favor of all new wiring (my new function with a different name). Why not just use the current getShipping() function name for my new code that determine the shipping cost for the item based on zip code? I figured this would work since the code on the key pages that used getShipping() would take me "home" to PayPal. Well, it worked, and all my shopping cart products, tax, and shipping costs made it through to "Checkout Success" and the transaction record shows up in the "sellers" PP Sand Box!