jQuery sum cells based on related checkbox selection

Here's how I would do it:

    var totalInvoice;
    $('input').on('change', function(){
        totalInvoice = 0;
        $('input:checked').each(function(){
            totalInvoice += parseFloat($(this).parent().siblings('td:nth-last-child(1)').text());
        });
        console.log(totalInvoice);
    })

Keep in mind that it is better if you specify the input that your referring to by a class or something.

I'd suggest:

// finding the inputs of type=checkbox, binding a change 
// event-handler:
$('table input[type="checkbox"]').on('change', function() {
  // finding the closest <table>:
  var table = $(this).closest('table'),
    // finding the checked checkboxes inside of that <table>:
    checked = table.find('input[type=checkbox]:checked'),
    // getting the last <td> from the <tr> that contains the
    // checked checkboxes:
    prices = checked.closest('tr').find('td:last-child'),
    // iterating over those <td> elements:
    sum = prices.map(function() {
      // creating a map containing the found prices, if the
      // trimmed text is not a number we return 0:
      return parseFloat(this.textContent.trim(), 10) || 0;
    // converting the map to an array, and passing it
    // to the reduce method:
    }).get().reduce(function(a, b) {
      // summing the current value (a) with new value (b):
      return a + b;
    });
  // setting the text of the element whose id="result":
  $('#result').text(sum);
// triggering the change event (in the case of any
// checkboxes being checked on page-load:
}).change();

$('table input[type="checkbox"]').on('change', function() {
  var table = $(this).closest('table'),
    checked = table.find('input[type=checkbox]:checked'),
    prices = checked.closest('tr').find('td:last-child'),
    sum = prices.map(function() {
      return parseFloat(this.textContent.trim(), 10) || 0;
    }).get().reduce(function(a, b) {
      return a + b;
    });
  $('#result').text(sum);
}).change();

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<table>
  <tbody>
    <tr>
      <th>Invoice #</th>
      <th>Date</th>
      <th>Balance</th>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="Invoices[]" value="" />Invoice 5</td>
      <td>2015-03-03</td>
      <td>75.97</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="Invoices[]" value="" />Invoice 8</td>
      <td>2015-03-07</td>
      <td>35.97</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="Invoices[]" value="" />Invoice 12</td>
      <td>2015-03-01</td>
      <td>30.97</td>
    </tr>
  </tbody>
</table>

<div id="result"></div>

References:

• CSS:
  • Attribute-value equals ([attribute=value]) selector.
  • :checked.
  • :last-child.
• JavaScript:
  • Array.prototype.reduce().
• jQuery:
  • change().
  • closest().
  • find().
  • get().
  • map().

You could do something like this: fiddle

var sum = 0;
$('input').click(function () {

    if ($(this).is(':checked')) {
        var price = $('.price');
        var add = ($(this).closest('tr').find(price).html());
        add = parseFloat(add).toFixed(2);
        sum += +add;
        console.log(sum);
    } else if (!$(this).is(':checked')) {
        var price = $('.price');
        var add = ($(this).closest('tr').find(price).html());
        add = parseFloat(add).toFixed(2);
        sum -= +add;
        console.log(sum);
    }

});