PHP Shopping Cart Error - php

Question

I'm making a shopping cart and I'm stuck on the actual cart. I've read a few questions on here and tried them but either they don't work for me, or they're plain rubbish.
PHP Code: addtocart.php
if(isset($_GET['product_id']) && isset($_GET['qty'])){
$product_id = $_GET['product_id'];
$qty = $_GET['qty'];
$cart = $_SESSION['cart'];
if($cart == null) {
$cart = array();
}
if(!isset($cart[$product_id])) {
$cart[$product_id] = 0;
}
$cart[$product_id] += $qty;
//var_dump($cart);
}
$session->setSetting("cart", $cart);
PHP Code: cart.php
try {
if(empty($_GET)) {
$cart = $session->getSetting("cart");
if($cart == null) {
throw new Exception("Empty cart.");
} else {
$template->setVar("cart", $cart);
} elseif($_GET['action'] == 'empty') {
unset($_SESSION['cart']);
header("location: /cart.php");
}
}
} catch (Exception $e) {
$template->setVar("errmsg", $e->getMessage());
}
Output:
<table class="table table-bordered table-striped table-condensed">
<?php foreach($this->cart as $product_id => $qty):
$item = $this->product->buildTotal($product_id); //var_dump($item);
?>
<tr>
<th>Items</th>
<td><?php echo count($item); ?>
</td>
<tr>
<th>Sub-total</th>
<td>
£<?php echo $price = number_format(($item[0]['product_price'] * $qty), 2); ?>
</td>
</tr>
<tr>
<th>Shipping</th>
<td>
£<?php echo $shipping = "2.95"; ?>
</td>
</tr>
<tr class="warning">
<th>Tax</th>
<td>20%</td>
</tr>
<tr class="success">
<th>Total</th>
<td>£<?php $tax = (($price * 20) / 100);
$total = ($price + $tax + $shipping);
echo number_format($total, 2); ?>
</td>
</tr>
<?php endforeach; ?>
Unfortunately, my error is that the totals table at the bottom of the cart displays 'x' amount of times for 'x' amount of products, example of two products makes the table display twice, rather than just totaling up the different prices etc. I've been stuck on this for three days so any help is greatly appreciated. Also, if your answer works, I'll list you in the credits page of the cart.