calculated columns - Dynamic jQuery add up totals and shipping and tax for invoice -

i having trouble adding calculations items add subtotal adding shipping input value , tax, e.g.:

item + item = subtotal  subtotal + shipping = total   total + 10% = grandtotal 

i calling class add items up:

$(document).ready(function() {     // add new row on invoice     var cloned = $('#invoice_tables .clone').clone();     $(".add-row").click(function (e) {         e.preventdefault();         cloned.clone().appendto('#invoice_tables');      });     //calculatesum();     $('#invoice_tables').on('change keyup keydown paste', '.txt', function() {         // updatetotals(this);         calculatesum();     });     //calculatesum();     $('#invoice_table').on('change keyup keydown paste', '.txt', function() {         // updatetotals(this);         calculatesum();     });      // remove row     $('#invoice_tables').on('click', ".delete-row", function(e){         e.preventdefault();         $(this).closest('.clone').remove();         calculatesum();     });     //iterate through each textboxes , add keyup     //handler trigger sum event     $(".txt").each(function() {         $(this).keyup(function() {             calculatesum();         });     }); });  function calculatesum() {     var sum = 0;     //iterate through each textboxes , add values     $(".txt").each(function() {         //add if value number         if (!isnan(this.value) && this.value.length != 0) {             sum += parsefloat(this.value);         }     });     //.tofixed() method roundoff final sum 2 decimal places     $("#sum").html(sum.tofixed(2));     //$("#sum input").val(sum.tofixed(2)); } 

the #invoice_tables coming database , #invoice_table added add new rows.

i have items description, quantity , cost. when these added work using #sum div. here need have shipping input value , calculate tax grand total.

i grateful ideas have tried adding new #sum2 not adding up.