This means tickets for the 24-strong horse race can cost no more than $20.83, a spokesman said.
Any money raised must be returned as prizes and no one is allowed to profit from organising the sweepstake.
Violating these regulations could incur a fine of up to $1000.
And beware of offering prohibited prizes. Firearms, liquor, tobacco and vouchers for sex services are all out of bounds.
Local singing talent Diane Tibble, runner-up on Maori Television karaoke show Homai Te Pakipaki, will be performing at the Rotorua Club for race day gatherers.
Club manager Nicky Newbrook said the club would be open from about 1pm onwards. "We've got sweepstakes, meat raffles and meal specials."
Those bold enough to dress up will also be eligible for the club's best dressed competition.
"There's a best dressed man and woman and best dressed hat," Mrs Newbrook said.
Kiwi punters are expected to bet about $8 million on today's Melbourne Cup.
One of the largest bets placed yesterday was for $5000 on Australian horse Ethiopia, a TAB spokesman said.
"If it wins, the lucky punter will stand to get something in the vicinity of $100,000."
In 2011, 14 per cent of Kiwis aged over 18 placed a TAB bet on the cup race.
This year, four New Zealand-bred horses will line up at 5pm (NZT) to compete for the NZ$7.77 million prize money.
Kiwi-bred horses Maluckyday, Lights of Heaven, Precedence and Zabeelionaire are among 24 stayers entered in today's race.
Patriotic punters will be watching Maluckyday which came second in the 2010 cup race.
New Zealand champion jockey James McDonald is also down to ride Irish horse Fiorente.
The race was last won by a Kiwi-bred and trained horse in 2001, when Ethereal took out the Flemington crown. The mare's victory was also the first Melbourne Cup race won by a female-trained horse.
Yesterday, reigning champion Dunaden was the race favourite. Commentators also expect French-trained Americain, which won the cup two years ago, to be in the mix.
Cup runneth over
Office sweepstake rules:
Prize must not exceed $500
Any money collected must be returned through the prize
Prohibited prizes include:
Firearms
Liquor
Vouchers for sexual services
Tobacco products
- Source: Department of Internal Affairs
Winning tips:
The race has been won most often (44 times) by a horse aged four years
The most successful sex is "entire", aka a male horse which has not been desexed (64 wins)
Numbers 4 and 12 are the luckiest numbers (11 wins each)
The race has been won six times each by horses starting the race from barriers 5, 10, 11 and 14
Jockeys wearing predominantly black or royal blue have been the most successful
The race has never been won by a horse starting from barrier 18
