Our main bathroom toilet has been leaking from the back awhile, we had it seal 4-5 times, and plus I've personally replaced the wax seal under neath is the seal bad or may it have a crack somewhere underneath that I can't see.

Pour some food coloring into the tank, and look to see where it leaks out.

IT may be comeing from the bolts that hold the tank onto the base, or comeing from the donut seal between base and tank If I have helped rate my answer at bottom hope I have helped.

After the toilet is set, does it sit flat or does it move when you use it? Have you looked to see if the leak is from the inlet piping? The tank to bowl connection? Is the floor flange at least 1/4" above the floor? Is the floor stable?