However, the fee was standard and applied to all transactions, no matter how much a ticket cost or how many tickets were being bought, he said.
"I guess it's a bit unfortunate if you're only buying one ticket, but if you're buying 10 it's a relatively negligible fee."
Mr McKenzie said the team had not received any complaints about the transaction fee, which was set by Ticketmaster.
The Blues' philosophy was for affordability, with standard children's ticket pricing across the board.
"If you bring your son, you can sit on halfway with him for $7, and you can sit at the end of the ground for $7 - it's your choice.
"So it's just a standard price for all kids."
Most children's tickets would be sold with adult tickets, he said.
"At a night game, I'm unsure how many parents would just be sending their young kids along by themselves unaccompanied."
Ticketmaster managing director Maria O'Connor said the processing fee was per order, regardless of the number ordered.
"Ticketmaster has to cover its operating costs ... labour, banking and credit card merchant fees, telecommunications, rent and general operating costs are expensed in every ticket we sell."