$(document).ready(function() {

    $("select#order_paper_size, select#order_sets, input#order_pages, select#order_shipping_type").change(function() {
      updateTotal();
      }); 
    });   


function updateTotal() {
  price = $("select#order_paper_size option:selected").val() * $("select#order_sets option:selected").val();
  $("#total").html("$" + price.toFixed(2));
};