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Zip codes are only used by the post office. You really don't need to include them when you give someone directions to your house, unless if there's more than one city with the same name in your state.
I take it back. I just tried to look up an address in a large city and Google Maps told me that there were two locations with that same address, in the same city, about a mile or two away from each other, but with different zipcodes. What the hell.