Unfortunately, there is no 10 word answer to your question. Sales tax laws are a local issue, and their content is different.

Generally, F.O.B. freight is sales tax exempt. Generally, Shipping and handling charges billed by the selling company are subject to sales tax.

However, each taxing authority has different rules, Ohio's laws are very different from New York or Iowa. And to make matters worse, cities and counties have their own rules.

I know as a web site coder this presents a nightmare scenario - I feel your pain.