Countdown's owner, Progressive Enterprises, started the service in its supermarkets in 1999 "but the technology just wasn't up to it at the time", a spokeswoman said.
A Lotteries Commission spokeswoman said that on average, supermarkets in the pilot programme had an 8 per cent increase in sales compared with similar supermarkets with separate Lotto counters.
The Progressive Enterprises spokeswoman said the wider introduction of the service began in January in stores throughout New Zealand.
Sixty-four Countdown supermarkets now had in-lane sales and the number would top 100 of Countdown's 160 supermarkets by the end of this month.
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Checkout sales would be restricted to some tickets, and not the full Lotto range, and would be in stores which already had Lotto. While some stores don't allow purchase of lottery tickets with credit cards, Progressive said all forms of payment would be accepted for checkout sales.
Tickets available at checkouts would be restricted to those that don't require customers to select numbers.
A spokeswoman for Countdown's rival Foodstuffs NZ, which runs New World, Pak'n Save and Four Square stores, said it was discussing offering the same service but she couldn't comment.
The Problem Gambling Foundation believes direct checkout sales of Lotto tickets could result in an increase in gambling.
Chief executive Graeme Ramsay questioned whether New Zealanders "really need to have lotteries products rammed down our throat".
"Having lotteries at every checkout of the supermarket is significantly different from a separate counter. It just makes gambling an everyday part of our lives and we shouldn't be thinking of gambling like that."
Groceries ... and a Powerball
Countdown has started selling some Lotto products at its supermarket checkouts.
The service is available at 64 Countdown supermarkets throughout New Zealand, and will be in more than 100 by the end of the month.
Tickets on sale at checkouts will be limited to three Triple Dip tickets, three Big Wednesday Dip tickets, three Powerball tickets and two Instant Kiwi tickets per customer.
Tickets sold from checkouts are printed separately on till receipt paper - they look different from the general shopping receipt and can be checked and redeemed at any Lotto outlet.
All forms of payment including credit cards will be accepted.
Tickets which require customers to select numbers will not be offered.
A trial of the service boosted Lotto sales by 8 per cent per store.
