Is there a way to limit the zip code field to only 5 characters? We have customers that are adding 'Zip+4' codes. (in the USA) (for example 90040-1025) and the tax is being calculated wrong. In the above example if they just put '90040' the tax would be calculated correctly.
The cart just uses the state(s) only to calculate taxes. Is this some modification you have that calculates tax off the zip code? If that's the case, the developer should easily be able to add some code to ignore anything more than the first five digits of the zip code.