Based on your screenshot, I can see you are using the Classic Designer.  I'm testing here with the Classic Designer on version 11.0.2212.30987.

The trick here is how the calculated formulas handle checkboxes.  In you go into a calculation on a field and use the variable picker, you'll see that it does not provide an option to pick the variable for the entire checkbox field, but just for specific values in the checkboxes.

Example:     =my_checkbox.FUL10225

And this formula just returns TRUE or FALSE based on whether the particular checkbox is marked or not.  It doesn't return a list of the checked values for the field.

So I'm not certain we're going to make this work in a meaningful way with the formulas.

Additionally - your values of the 1st, 2nd, 3rd, etc. will all be automatically changed to include a V_ before them because checkbox values in Forms cannot start with a number.  So you might need to decide on a different way to do those values so that they are not starting with a number.  For my testing, I just used D01, D02, D03, etc. (to mean District 1, District 2, District 3, etc.)

But, the good news is that we can always do a script to achieve your needs for this total of the checkboxes.  Here's a Javascript that should work.  This assumes your checkbox field has a class name of myCheckboxes, and the total field has a class name of myCalculation. 

$(document).ready(function() {
  
  //Run the calculation function when the form is first loaded.
  CalculateMyCheckboxes();
  
  //When changes happen on the myCheckboxes field, run the calculation function.
  $('.myCheckboxes input').change(CalculateMyCheckboxes);
  
  //Calculation function for the checkboxes.
  function CalculateMyCheckboxes() {
    var costTotal = 0;
    $('.myCheckboxes input:checked').each(function() {
      var checkboxCost = parseFloat($(this).val().substring(5, 99));
      costTotal = costTotal + checkboxCost;
    });
    $('.myCalculation input').val(costTotal);
  }
  
});

                        225 + 30 + 75 = 330