We know Magento support multiple currency. Use following code given below to check current currency in the Magento site frontend.

To get current currency code

<?php echo $current_currency_code = Mage::app()->getStore()
->getCurrentCurrencyCode(); ?>

If you looking for current currency symbol use :

<?php echo Mage::app()->getLocale()->currency(Mage::app()
->getStore()->getCurrentCurrencyCode())->getSymbol(); ?>