"But we've got to remember retail isn't just one month of the year, it's 12 months of the year."
This year had seen a turnaround in the retail sector, with more than 5 per cent growth month on month up to the end of November, he said.
"In conjunction with all that, you've had the improvement in business confidence, the improvement in consumer confidence, unemployment is below 6 per cent and house prices are increasing.
"That gives people that sense of increased wealth and leads on to what we call the 'feel good' factor, which translates into spending."
Other factors such as increased immigration and tourism had also contributed to sales.
"What we're finding is that tourists no longer just shop at the specialist tourist shops, they shop across the board."
Paymark's head of sales and marketing, Paul Whiston, said the 12 per cent increase was "a fair bit higher" than anticipated.
He had expected Christmas Eve to be strong, but Boxing Day sales were always variable due to the weather.
"On a sunny Boxing Day, people tend to head to the beach a bit earlier but I know it was a bit inclement round most of the country ... so maybe people thought, 'Let's just go to the mall and do our returns or swaps or vouchers'."
Boxing Day deals brought the shoppers in, sales at clothing and jewellery stores rising 16.5 per cent, at appliance and whiteware stores 16.6 per cent, at electronics retailers 12 per cent and at floor covering and furniture stores 17.5 per cent.
Shoppers in the Auckland and Northland regions spent 13.2 per cent more than last year in Boxing Day sales, while Canterbury shoppers spent 15.1 per cent more.
Mr Whiston said it was good to see some of the small regions reaping the benefits. "Gisborne saw the highest growth on Christmas Eve, up almost 36 per cent on the previous year. And [on Boxing Day] Wairarapa saw an extra $200,000 injected into its local economy, an increase of 17.2 per cent on 2012."
A spokeswoman for The Warehouse, Jenni Ryan, said many stores had customers queuing at the door in the morning.
Technology, camping gear, barbecues and toys had been popular but she was unable to comment at this stage on whether this year's sales figures had exceeded 2012's.
• 2013: $134.4 million, up 12 per cent
• 2012: $120 million, up 13.4 per cent
• 2011: $105 million, up 6.9 per cent
• 2010: $98.9 million, down 2.8 per cent