The rate is 100 dollars per night, not including tax.
Literal
Fee [topic-は], tax-excluded [basis-で] one-night 100 dollars is.
税別 (tax-excluded) is a compact compound common in pricing: 税 (tax) + 別 (separate). 一泊 uses the counter 泊 for overnight stays — 二泊三日 (two nights, three days) is another common pattern with this counter.