"It's very confusing," Ms Doherty said.
"We looked it all up before doing the surcharge. It was only because on the official Government website, it said the official holiday was Saturday."
Yesterday was the first time the Mondayisation of a public holiday came into effect in New Zealand.
"Closing for a holiday was no option. We are open seven days a week, no exception really, except for Christmas and Easter."
Ms Doherty said the cafe was one of only a few hospitality venues open yesterday.
"Today the cafe next door was open for a few hours before closing, then Subway was open but there's not much else open. As a result, we've been extremely busy."
Waitangi and Anzac days only fall on a weekend about twice every seven years.
For employees who would not otherwise work on a Saturday or Sunday, the public holiday must be treated as falling on the following Monday. For employees who would otherwise work on that Saturday or Sunday, the public holiday must be treated as falling on that day.
The idea for the bill came in 2010 when Anzac and Waitangi days both fell on the weekend - that year New Zealanders got only nine of the 11 public holidays allowed under the Holidays Act.