Javascript Calculate Form

Avg Bid (USD)
Project Budget (USD)
$30 - $250

Project Description:
I had a form with a running total working until I was asked to add some checkboxes. Here is what I have:

The final total field must be a running total and read-only like it is now. The first section works, but I can't get any part of "Make Additional Donation" add to the total.

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