You (or someone) would need to code this - there's nothing available that I know of that will provide this function. There is this:

http://www.zen-cart.com/index.php?ma...oducts_id=1070

I haven't used it, and don't know how easy (or difficult) it would be to add zones, but it might be a place to start.

Part of the problem with your question is that I'm not familiar with any shipping provider (in the US, anyway) that only considers zip codes to determine rates. Maybe if you let us know what shipper you're planning on using, we might be able to offer better advice.