As of 2pm, $166 million had been put through the tills.
The busiest time of the day has likely passed, with a peak of 204 transactions per second at 12.30pm, a new record.
The previous record was 188 per second and the daily average about 60.
Paymark chief executive Maxine Elliott said they had to work hard to ensure the retail network was fully operational throughout today.
Paymark had seen about 3 million transactions processed since midnight.
Company spokesperson Paul Brislen told Checkpoint the pandemic had not been bad news for retailers at all, and most would be quietly pleased with this year's spend up.
"We've seen really quite an impressive bounce back - not evenly distributed of course, not right across the board - but in a lot of parts of the retail economy spending has been as good as last year if not better."
He said food and beverage retailers, home and recreation, and clothing and footwear had a "huge" dip during lockdown but had since been trading similar to last year's numbers.
Tourism retailers, however, were unsurprisingly not doing well, he said.
Brislen said the overall figure for retail spending on Christmas would be much higher than what Paymark reported as it did not include online sales and other Eftpos machine providers in its statistics.