How do I add a subtotal, tax. total?

It seems that you have already figured out adding sub-total by using the calculator widget. Similarly, the tax and total can be calculated using calculator widget. For example, 5% of tax can be calculated on subtotal as below :

I see that you are collecting credit card information using plain text fields which is not allowed through JotForm. Such forms are considered as phishing forms and the accounts associated with these forms will be suspended. Please refer to our terms of usage for more information on phishing. Hence, we request you to remove the guilty fields from your JotForm immediately.

Also, please note that the order forms are made easy using one of the payment tools available with us.

The subtotal and taxes can also be calculated using these payment tools. Please refer to the guide below to add taxes to your order form.

http://www.jotform.com/help/296-How-to-Add-Tax-to-Your-Payment-Form

Hope this information helps. Please get back to us if you need any further assistance. We will be happy to help.

Thanks!