function calcSum()
{
  var text = '';
  var sum = 0.0;
  var quantity = 0;
  for(x in price_data)
  {
    if( document.getElementById('itemSel'+x).checked && price_data[x] != '' && parseFloat(document.getElementById('itemSelQ'+x).value) > 0 )
    {
      quantity = document.getElementById('itemSelQ'+x).value;
      sum = sum + parseFloat(price_data[x] * quantity);
      text = text + '\n' + price_data[x] + ' - ' +x;
    }
    
  }
  
  if( isNaN(sum) )
    return;
  
  var sum_with_pvm = sum * 1.21;
  var pvm = sum_with_pvm - sum;
  
  document.getElementById('without_pvm').innerHTML = sum.toFixed(2);
  document.getElementById('pvm_only').innerHTML = pvm.toFixed(2);
  document.getElementById('with_pvm').innerHTML = sum_with_pvm.toFixed(2);
  
  
  document.getElementById('sum_without_pvm').value = sum.toFixed(2);
  document.getElementById('sum_pvm').value = pvm.toFixed(2);
  document.getElementById('sum_with_pvm').value = sum_with_pvm.toFixed(2);

  //alert(text + ' CHEKED=' + sum.toFixed(2) + '  NOFIX=' + pvm.toFixed(2));
  
}

function checkInput(obj)
{
  if( isNaN(parseInt(obj.value)) )
    obj.value = '1';
  else
  {
    if( parseInt(obj.value) < 1 )
      obj.value = '1';
    else
      obj.value = parseInt(obj.value);
  }
}