"Everyone wants to win the big money," he said.
Yu placed their popularity on their reputation as a store for caring about their customers, he said.
The latest big win they had sold the tickets for was a $24,000 win just last week, Yu said.
But with the massive jackpot coming up, customers had started to wait outside the shop before they opened, he said, and today would be "very busy".
Yu said most people didn't get the same numbers, however.
"Each number is random," he said, which meant that people would rather choose a lucky dip which produced a random draw of numbers on the ticket than choose their own.
Jenni Wiles, a shopper at Bayfair Lotto, just laughed when asked why she was buying a Lotto ticket this week.
"I have dreams that if I win this I would have a chance of travelling or doing things that I really want to do, but can't afford to do," she said.
She didn't buy a ticket every week but would buy one if she "had enough spare cash", she said.
"Maybe once a month, roughly - but this time I am buying it because it's the big one."
Wiles' husband was "chipping in" as well - "and he never does that", she said.
She doesn't buy the same numbers every time, either.
"I just rely on random because the balls come out randomly and if the machine is random ... I just thought that a random choice is as safe as anything."
Marie Winfield, Lotto NZ head of communications, said Tauranga has 44 Lotto outlets.
The luckiest Lotto store for Powerball wins in Tauranga is Greerton Lotto, she said, which has sold three of the winning Powerball tickets since 2001.
She said the biggest Lotto prize won in Tauranga was a $27m Big Wednesday scoop in 2012. The ticket was sold at AJ's Lotto and Tobacconist on Devonport Rd.
Lotto had seen "a significant increase" from last week both in stores and online sales, Winfield said.
"With Powerball jackpotting to one of the highest amounts we have ever seen, excitement is certainly building."
What would you spend $42 million on?
Christine Banks, 61, Pāpāmoa East
"Give it to my family, charities, things like that."
Jonas Klaumunzner, 42, Switzerland
"Probably just enjoy the rest of my life, travelling."
Christy Hawker-Cunliffe, 38, Pāpāmoa
"I would invest in new Zealand businesses."
Sally Merldre, 25, Mount Maunganui
"A house, travel around the world, those are my main goals."
Peter Materna, 35, Tauranga
"Buy a house, maybe an island."