Accommodation spending was modest, up 5.6 per cent, which suggested a lot of fans pre-paid for their rooms.
Car rental spending was up 7.9 per cent, while clothing stores saw a 28.8 per cent increase on Sunday.
Mr Whiston said the extra spending followed weeks of slow growth for the region.
"The Wellington region ranked low for total spending growth through Paymark during September and has remained weak in early October.
"Between Friday and Sunday, it's fair to say that cup fans added a much appreciated boost to the capital's economy."
Foreign tourist spending in Auckland and Northland was up 66 per cent, or $2.8m the same three days.
An extra $2m was spent on hospitality, peaking on the Sunday when the All Blacks beat Argentina 33-10 - up 20.2 per cent. Accommodation spending was up 10.8 per cent over the three days.
Total foreign card spending through Paymark's network was $172.7m since the cup started, up $46.9m on the same period last year.
Mr Whiston said hospitality had been the big winner in terms of foreign spending, but tourists were also spending their money on things outside pubs, clubs, rental cars, and accommodation.
"However, general spending patterns are still modest - perhaps while the tourists are making the most of the cup's hospitality, Kiwis are continuing to keep a close eye on their dollars," he said.