Edit in JSFiddle

var productobj = {};
$(function() {
	$('input').on('keyup', function() {	
  	var uid = $(this).data('uid');
    var product = productobj[uid];
    product[$(this).attr('name')]=$(this).val();
    product = validate(product);
  	productobj[uid] = product;
    computesum();
  });
  
  $('button.product-add').on('click', function() {
    var source = $('#product-item-new-tpl');
    var item = $('#product-item-modify-tpl div.product-item-modify').clone(true);
    var uid = Date.now() + Math.random();
    var product = {};

    source.find('input[type="text"]').each(function() {
      var el = $(this);
      var inputtext = item.find('input[name="' + el.attr('name') + '"]');
      inputtext.val(el.val());
      inputtext.data('uid', uid);
      product[el.attr('name')] = el.val();

      if (el.attr('name') == 'quantity') {
        el.val(1);
      } else {
        el.val('');
      }
    });

    item.find('button.product-remove').data('uid', uid);


    product = validate(product);
    if (!product.status) {
      // highlight the product row
    }

    productobj[uid] = product;

    $('div.tindahan-product-list').append(item);

    console.debug('product list', productobj);
    computesum();
  });

  $('button.product-remove').on('click', function() {
    delete productobj[$(this).data('uid')];
    $(this).parent().remove();
  });
});

function validate(product) {
  product.status = true;
  product.quantity = parseInt(product.quantity);
  product.price = parseFloat(product.price);
  if (Number.isNaN(product.quantity)) {
    product.quantity = 1;
    product.status = false;
  }
  if (Number.isNaN(product.price)) {
    product.price = 0.00;
    product.status = false;
  }
  return product;
}

function computesum() {
  var totalsum = 0;
  $.each(productobj, function(index, product) {
    var itemsum = product.price * product.quantity;
    totalsum = totalsum+itemsum;
  });
  $('#tindahan-product-total').html(totalsum.toFixed(2));
}

<div>
  <div class="tindahan-product-list">
  </div>
  <div id="product-item-new-tpl" class="product-item-new">
    <input type="text" name="name" placeholder="Product">
    <input type="text" name="price" placeholder="0.00">
    <input type="text" name="quantity" value="1">
    <button class="product-add" class="">+</button>
  </div>
</div>
<div id="product-item-modify-tpl" class="hide">
  <div class="product-item-modify">
    <input type="text" name="name" placeholder="Product">
    <input type="text" name="price" placeholder="0.00">
    <input type="text" name="quantity" placeholder="Quantity">
    <button class="product-remove">x</button>
  </div>
</div>

<div class="tindahan-fixed-bottom">
  <span>Total:</span> <span id="tindahan-product-total"></span>
</div>

input[name="price"] {
  text-align: center;
  width: 44px;
}

.hide {
  display: none;
}

input[name="quantity"] {
  text-align: center;
  width: 22px;
}

.hide {
  display: none;
}


body {
  background:#222;
  color:#fff;
  font-family: consolas
  
}
body, input {
  font-size:14px;
}

input { 
  background:none;
  color:#fff;
  width:120px; 
}

h1 {
  font-size:18px;
}

h2 {
  font-size:16px;
}