what 割増 means?
 

saw in front of taxi

Hi. It's warimashi and it can mean: premium, bonus, extra wages.

That's the night-time surcharge on taxi fares in Japan.

warimashi (割増) is the opposte of waribiki (割引), "discount."

thank u, u know how much more they charge?

Legally speaking, a taxi company can charge anywhere between 25 ~ 50%. In actual practice, most companies seem to charge about 30%.

got that
thank u very much