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Depending on what you are looking for.
In your calculation, this is how it should work:
freight + (subtotal * 8.25%) = total.
Here's a sample form: http://form.jotformpro.com/form/52090720458958?
Here's how my form calculation widget is set:
I also checked your form and it seems to work as expected:
Let us know if the calculation is still incorrect and please provide us more details of it.