Why are we getting more retainers?

[Erendis]

I have only seen the tax discount once and that was during open beta. Ever since, I have seen it at the normal rate for every city. What is it that affects tax rate? I have heard that it depends on the number of retainers dispatched to a city.

I have seen tax reduced to 3 % in Limsa Lominsa a few times after release, however it has been a while.