City tax, tourist tax, occupancy tax, visitor levy, taxe de séjour, imposta di soggiorno: the name and the rules change from town to town. In some places the guest owes the tax and you collect it; in others the tax is yours and you may pass it on. Either way, the authority looks to you for the right amount. Charge too little and the difference comes out of your pocket; charge too much and you owe a guest a refund.
Every rule answers the same five questions: what is charged, who pays it, for how many nights, at which rate on which night, and whether VAT is added. Set up each tax so it gives those answers, show it on its own line before the guest pays, and keep the night-by-night figures your return asks for.

