The Retailers Association says a variety of conditions worked in retail owners' favour this year to send Boxing Day sales soaring.
According to electronic transaction processer Paymark, shoppers put $120 million into retailers' coffers on Boxing Day - $14 million more than the same day a year ago.
Association spokesperson Barry Hellberg says the stars aligned for retail owners this year, as the weather in some parts of the country encouraged many people to head for the shops instead of the beach. "The wet weather in the northern part of the North Island was clearly a factor which perhaps encouraged more people to go to shops," he said.
Mr Hellberg says it is also becoming common for people to receive gift cards on Christmas Day, which they are then likely to use on Boxing Day.
Paymark, which processes 75% of all electronic transactions, says spending on Thursday was up 13.4% on Boxing Day 2011.
The biggest increase was in electronic retail sales, up 31.7%. A lot of money was also spent on clothing and jewellery.
Meanwhile, unwanted gifts have been turning up on the auction site Trade Me, and by Thursday night almost 2000 were listed for sale. They range from watches, electronic equipment and clothing to picture frames and board games.