Cron not running at interval

[yurividal]

I have set CRON_INTERVAL to 5, and set 5 on the admin panel.
But, my cron seems to be running only every 10 minutes. Its like its failing every other time.
I tried manually executing
/usr/local/bin/php -c /usr/local/etc/php/php.ini /data/upload/api/cron.php
and the first time i execute it, it seems to run in less than a second, and the second time it actually runs. So, its definitely skipping every other try.