Some fields having underscores in their field tag are not being summed by Form Calculation widget

My rush order and shipping checkboxes are not working in the total calculation widget. 

I took a look at your jotform http://form.jotform.us/form/51748212737155 and I can confirm that it is not working, but as I made a check of your Form Calculation, I have seen that the checkboxes in question are not even included in it - which is why they are not being added.

This is the current setup (not including the checkboxes):

and this is with the fields added up:

Now, there is just one thing to note and that is that your fields had underscore in their tag, which does not seem to be accepted by our form calculation at this time (for which I will raise this thread to our developers), but as soon as you change the field tag to use dash instead, it will work properly.

So this is the modified clone of your form where you can see it in action: http://form.jotformpro.com/form/51805968864976

If you wish you can make the change to your jotform, or just simply clone the jotform above to your account and use it instead. To see how to do that you should take a look at the following guide: How to Clone an Existing Form from a URL

Do let us know if there is anything else that we can assist you with.

Just to mention. To see the field tag and edit it you should take a look at the following guide: How to find Field IDs & Names