Recently I purchased exercise equipment from a nationwide exercise equipment store.
I returned it within 30 days. All of the piece were never delivered to the house. Merchant wants to keep 20% plus the tax. I total of 660. Dollars. I financed this through a credit card company?

Not legal if you never received the complete package. If the store won't back do deny the charge via your change company. Review all of your paperwork and ordering forms to see what you may have agreed to but didn't notice the first time around.

If you are returning this because you never received the full package, then its not legal and you should file a protest with your CC.

However, it IS legal to have a restocking fee on certain returned merchandise. But that has to be clearly noted at time of purchase.