Magento 1.7 – How to Get Bundle Product ID Using Bundle Item

The price of a bundled product is calculated in the class Mage_Bundle_Model_Product_Price, in the function getFinalPrice() to be exact. When you look into this function you’ll notice two lines in particular:

$finalPrice = $product->getData('final_price');
$finalPrice = $this->_applyOptionsPrice($product, $qty, $finalPrice);
$finalPrice += $this->getTotalBundleItemsPrice($product, $qty);

And for tax

You can get a helper-instance in any file using:

Mage::helper('tax')

Your full code is:

$_product = Mage::getModel('catalog/product')->load($productId);
$_priceIncludingTax = Mage::helper('tax')
    ->getPrice($_product, $_product->getFinalPrice());

EDIT

or you can also use direct function to display price with tax

Mage::getModel('bundle/product_price');
public function getTotalPrices($product, $which = null, $includeTax = null, $takeTierPrice = true)

See for calculation

hope this will sure help you.

you get all bundle product ids by using below code

$childrenIdArray = Mage::getResourceSingleton('bundle/selection')
            ->getChildrenIds($parentId, $required=true);