Total spending by families and individuals on food, drink and gifts during the festive season will top €4 billion, the Small Firms Association (SFA) said.
"The Christmas spend will go over €4bn," said SFA director Pat Delaney.
"We would have forecast an 8% rise nationwide over last year, but we would have upgraded that now to 10%.
"The total spend will be the equivalent of about €940 for every man, woman and child in the country."
The €4bn estimate refers to consumer spending only.
When corporate spending is factored in, the total will be several billion higher.
The Dublin Chamber of Commerce said €3.7bn of retail sales will be rung up in the greater Dublin region alone over the Christmas period. Some €2.5bn of this will be spent in shops, restaurants and pubs in the city centre.
With sales in the Dublin region accounting for roughly one-third of the nationwide total, it means over €11m could be spent across the country by the consumer and corporate sectors combined.
"It's been a very, very strong year for retailers," Mr Delaney said.
"And it looks obvious now that there's going to be a very, very strong sales season as well. This time last year, there was very little confidence around.
"People may have been worried about their job prospects, or they may have been worried about interest rates going up.
"What's happened this year, looking at the overall situation, (is that) we have full employment, we have interest rates at a 15-year low, we have historically low inflation, and we have GDP growth of about 5.5%. So the economy is very strong, but the most important thing that's happened is that confidence has returned."
The bounce in sales is consistent with consumer sentiment expressed ahead of the Christmas period.
A survey carried out by Deloitte in November found almost one-in-three people intended to spend more this Christmas than last year. It also found consumers planned to significantly outspend their European counterparts, possibly by as much as €545 per household.