Tip to hide the price of the product if Magento user is not logged in

 To show tiered pricing to logged in visitors only, go to: app/design/frontend/default/default/template/catalog/product/view/tierprices.phtml
 
On this file, add this PHP function

  <?php if(Mage::getSingleton('customer/session')->isLoggedIn()): ?>

The above function should be added before the following piece of code 

<?php if (count($_tierPrices) > 0): ?>

Then add this code at the end.

  <?php endif; ?>