The average transaction was just under $50.
"A lot of sectors have showed some strong spending patterns through the month of December and many retailers will be very pleased with the results," Mr Whiston said.
Pet stores recorded some of the month's highest growth (9.2 per cent).
Owner of Animal Antics in Mt Maunganui, Ross Mitchell, said the end of the year saw a jump in customers. "We sold a lot more stuff [and] we probably made more money. But people weren't buying big-ticket items like big fish tanks, rabbit hutches and kennels."
People were spending more on pets and pet supplies as the economy improved, but more of this was being spent online than in shops.
However, fish sales surged as parents bought fish tanks for their kids for Christmas.
Kiwipetz manager Aliesha Goile said she noticed an increase in sales in December with people not only buying pets but buying Christmas presents for their pets.
She said people were also going to the Fraser Cove store to buy items (for their pets) to take on holiday with them.