Cityprom executive officer Vanessa Cahoon said retailers had reported a boom in spending over the past 10 days, with today tipped to be the busiest so far.

"The first couple of weeks of December were certainly a worry. Our members were telling use there wasn't much of an increase in business at all," Ms Cahoon said.

"But now it's certainly snowballed in terms of traffic and sales; our members are telling us that sales have increased every day."

Ms Cahoon said retailers were divided over whether this year's sales were comparable with last Christmas.

"A couple are saying it hasn't been as strong - particularly in the electrical sector, where shoppers have indicated they're waiting for Boxing Day sales until they buy those big-ticket items," she said.

Ms Cahoon said popular buys this year had included clothing, iPods, iPod docking stations and e-readers.

She said Boxing Day was also expected to be a big day for retailers.

"Feedback from customers indicated that they are holding off on pre-Christmas purchases in the hope of saving some extra dollars in the post-Christmas sales," she said.

Australian Retailers Association executive director Russell Zimmerman said $14.8 billion was expected to pass through tills Australia- wide between Boxing Day and mid-January.