Sometimes it is worth it, like if you want to build up feedback from scratch, or protect yourself from the impact of one negative.
ebay.com (USA) has just announced a reduction in fees specifically for this price category , so I presume we will follow suit.
But overall, yes, not worth listing. I've stopped really listing below �10 now.
ALSO, I find almost without exception that buyers of low value items are MUCH more likely to leave negative feedback unjustifiably , and bid, win, and don't pay , more often.