"It's not only children who have been coming into the shop but grandparents with their grandchildren, and adults wanting something for a work party.
"From last weekend it started to snowball and it won't stop until Christmas. We will get people coming in for follow-up parties looking for fancy dress to wear."
A number of the store's bigger spending customers were Americans living in Rotorua, she said. "It doesn't matter how bad the economy is, it is important to keep happy."
The Warehouse manager Sally Rison said they were selling lots of lollies and costumes. "We have had a wide range of novelties being bought by children and adults, not just for trick and treating."
Staff plan to dress up in Halloween costumes tomorrow in store, she said.
Rotorua Senior Sergeant Brendon Keenan said parents should accompany children while trick or treating.
Children knocking on homeowners' doors should respect private property and appreciate owners, especially the elderly, who might feel vulnerable, he said.
Rotorua District Council parks and recreation manager Garry Page said Halloween had been pretty trouble-free for the council-owned facilities.