While developing a WordPress plugin which was relying on wp_cron I had to debug function that was called with the wp_cron. There was a need to run the cron every few minutes. Here is the solution:

Add following code to your plugin

add_filter('cron_schedules', 'new_interval');

// add once 10 minute interval to wp schedules
function new_interval($interval) {

    $interval['minutes_10'] = array('interval' => 10*60, 'display' => 'Once 10 minutes');

    return $interval;
}

Now you can use your time interval in wp_schedule_event

function InitiateMyCron() {
    if (!wp_next_scheduled('MyCronEvent')) {
        wp_schedule_event(time(), 'minutes_10', 'MyCronAction');
    }
}

Finally the function called by wp_cron

function MyCronAction() {
    //do my cron
}