National Australia Bank says Boxing Day transactions through its EFTPOS, ATM and credit card terminals were up around 30 per cent on last year.
The bank says more than 3.8 million transactions were conducted through its equipment, with a peak rate of 100 per second.
Transactions peaked at 1:00pm on Boxing Day, however it was not the busiest shopping day this month, with last minute Christmas Eve shoppers driving transactions as high as 207 per second, and 7.7 million transactions on December 20 (the Thursday before Christmas) with a peak rate of 182 per second.
Part of the growth appears to be due to the increased use of plastic over cash, with electronic transactions on NAB's network up 15 per cent over the past year, despite lacklustre growth in retail sales.
The Australian Retailers Association expects $14.8 billion will be spent around the country from Boxing Day to mid-January.
ANZ economist Ivan Cohoun says solid customer traffic in stores and online also will not necessarily translate to a strong post-Christmas retail profit result.
Mr Cohoun says between 30 and 35 per cent of the whole year's retail spending occurs in December, but he says goods are usually a lot cheaper at that time, so retailers have to sell more to make a profit.
"The comments from the different retailers are suggesting that there has been good volumes but, of course, after Christmas, it's normally at reasonably discounted prices," he observed.
"So that doesn't necessarily suggest the consumer is being very confident, but continuing to search for bargains." Mr Calhoun says 2012 has been another challenging year for retailers, and 2013 is not looking much better.
"It does seem to have been a little bit better around Christmas and Boxing Day," he added.
"But most of the comments we're seeing are saying, 'look it's been good but not great', and I think most of the outlook still says it's going to be quite challenging for many retailers into the new year, unfortunately."