What's the appeal?
Boxing Day sales are an ingrained part of Kiwi culture.
That's the view of consumer behaviour expert and senior marketing lecturer at Auckland University, Dr Denise Conroy.
Shoppers can already get lots of good deals throughout the year as there are regular sales, she says. Online shopping also offers cheap prices, especially as many outlets provide free shipping to New Zealand.
But despite this, people still flock to the shops on December 26 in search of cut-price appliances, cheap clothing and clearance stock electrical goods, Conroy says.
"It's a tradition here the same as it is in Canada, Australia and the UK. And it's the tradition thing and the hype around it that keeps us going."
Are the deals really worth it?
"Store-buster" deals are definitely on offer post-Christmas, but shoppers have to be realistic in their bargain hunting, Conroy says.
"They [retailers] will have genuine, absolute, incredible bargains but they'll be very limited and if you're not first in the door then you're a lot less likely to be getting that incredible bargain.
"For the rest of us - it's a case of either be disappointed or perhaps be more realistic and say 'I'm going to get 20-25 per cent off something'."
Taking a quarter off the price is a decent discount, but not unusual compared to deals available throughout the year, Conroy says.
Retailers know Boxing Day shoppers, who have to compete with crowds and packed-out car parks, are likely to spend once they reach their shopping destination.
"Even if you've missed the dishwasher, or dress, or whatever it was you were going for, you're more likely [to spend] because you've invested in terms of the hassle of getting there."
Do I really need to queue?
Not necessarily. Week-long, post-Christmas sale extravaganzas, also known as "boxing week", are becoming more common, Conroy says.
But she warns that as with the traditional one-day December 26 sales, the best deals will be the first products to fly off store shelves.
However, shoppers should still be able to pick up cheaper products during the week.
The Retailers Association says stores are more likely to invest in a week-long sale, rather than relying on just a one-day selling frenzy.
"Most of the promotions will last through to the end of the week," chief executive John Albertson says.
Retailers have to put up additional signs, display cards and advertise, so holding a sale that lasts for more than one day is often beneficial.
What's in it for retailers?
Boxing Day shoppers spent nearly $106 million last year, according to retail figures from electronic data company Paymark. This was about 7 per cent up on the previous year's spend.
But how valuable is it to retailers if most things are being sold at discount?
Albertson says Boxing Day sales enable shops to get rid of leftover Christmas stock.
"Retailers obviously build stock significantly for the Christmas period. Invariably, someone's going to get left with stock in excess with what they need," says Albertson. "The best thing a retailer can do is convert their stock to cash as quickly as possible and reinvest it back into stuff that is selling at regular prices."