When you start creating virtual hosts under NGinx and give them separate access and error logs don't forget to update the logrotate configuration otherwise your logs just keep growing.

I have named my logs with .access and .error extensions instead of the default .log option so that has necessitated the following change to the /etc/logrotate.d/nginx file

/var/log/nginx/*log /var/log/nginx/*access /var/log/nginx/*error {
    daily
    rotate 10
    missingok
    notifempty
    compress
    sharedscripts
    postrotate
        /bin/kill -USR1 $(cat /var/run/nginx.pid 2>/dev/null) 2>/dev/null || :
    endscript
}