var $costs = $('.tli-textbox-list td input.cost');

$costs.bind('click mouseover keyup change', function ()
{
    sum_costs();
});

sum_costs();

function sum_costs()
{
    var cost = '';
    var cost_sum = 0;

    $costs.each(function ()
    {
        if ($.trim($(this).val()))
        {
            cost = $.trim($(this).val().replace(/[$,-]/gi, ''));
            cost_sum += parseFloat(cost, 10);
        }
    });

    var total = $('.tli-textbox-list td.amount');

    if (isNaN(cost_sum))
    {
        total.html('<span style="color: red;">Some Costs Are Invalid</span>');
    }
    else
    {
        total.text('$' + parseFloat(cost_sum).toFixed(2));
    }
}