Cool. I just looked it up, it was a 3% tax according to a source, that was levied on property, and some flat license fees that were really tiny if you engaged in trading. Like if you bought yourself a place to trade in a market you rented out that place for a flat fee.

But other than that, absolutely no other taxes: no income tax, no sales tax, nothing else.

And there weren't even that many slaves in the beginning. And most slaves were housemaids, or people who worked in the garden.

Most farming jobs were done by the peasants, so slaves in some cases had better quality life than the farmers.

It was more like servants than slaves. They had full rights to move in the city, to marry, or even to buy property.

So it wasn't that harsh slavery as the other forms of that time.