You can follow those below codes to get products tax percentage magento:

$store = Mage::app()->getStore('default');

$request = Mage::getSingleton('tax/calculation')->getRateRequest(null, null, null, $store);

$taxclassid = $product->getData('tax_class_id');

$percent = Mage::getSingleton('tax/calculation')->getRate($request->setProductClassId($taxclassid));
POST HASN'T TAG.