Please tell me if I am supposed to charge sales tax to a New Jersey
company for work we did in New York. The product we created was
produced and delivered to a New Jersey address.

Dear jn343

In a word, NO.

You have, what's called nexus, in New York.
All your work is done in NY.

You don't do work in New Jersey. 

However, your buyer may find that they need to pay USE TAX
on that purchase in New Jersey. 

You'll find a pretty good explanation of the rules related
to collecting sales tax in the second part of an article
about taxes related to eBay sales:

http://cbs.marketwatch.com/news/story.asp?page=2&param=archive&guid={62AF0911-7A82-4122-BA9B-7F14230A2509}&siteid=mktw

I hope this helps?

Best wishes,

Your TaxMama-ga

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