http://www.clubosc.com/usa-tiered-shipping.html

This contribution allows the Store owner to set a cost for: 1st item + more items + handling fee for selected states

A real world example
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You want to charge $10 for the first item, and 50 cents for each extra item ordered.
You want to add a $24.95 shipping charge for Hawaii and Alaska
12 items sold in the order.

This contribution will give a quote of:

To Hawaii: $40.45 (this being: 1*$10 + 11*$0.50 + $24.95)
To Alaska: $40.45 (as above)
To all other US states: $15.50 (this being: 1*$10 + 11*$0.50)

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