Add total price in checkout success page

How to add in magento success.phtml order's total price? After placed order, customer get all info how to make payment including what price need to pay, because customer don't remember in last step what is total price.

You could use something like this in your success.phtml:

$sOrderId = Mage::getSingleton('checkout/session')->getLastOrderId();
$oOrder = Mage::getModel('sales/order')->load($sOrderId);
echo $oOrder->getGrandTotal();