[jeanne]

If the tax zone is looking for cities then the only way that you will get taxes to show with the zip code estimate is to either build a routine in cart.php that will translate the zip to a city or set up your tax zone by zip code.

if($zipcode_estimate >= 10001 && $zipcode_estimate <= 10002){
$config["General"]["default_city"] = "A City";
}elseif($zipcode_estimate >= 10003 && $zipcode_estimate <= 10004){
$config["General"]["default_city"] = "Another City";
}

(I don't know what the correct zip codes would be.)

I think that it would be easier to set up your tax zone up by zip code though so if you needed to change any zip codes you would not have to dig through the code.