Thanks for the reply, that link works for me. But I thing I wants to know. If I just wants to add Tax Code for only NJ, then why I needs to add all and remove the unwanted items?
You don't have to add all the tax codes and remove those you don't need. There are three fields in that form. Choose the country as US, enter NJ inside Tax Code: field and specify the "Tax Rate percent (between 0 and 100):" inside the % field. Then click save. Try it. It's really liberating. I just created few of them myself.