Consumers opened their wallets with gusto last month as Covid-19 restrictions were relaxed.
Official data showed a seasonally adjusted 78.9 percent increase in electronic card spending after hitting record lows in April.
The strongest rise was for durable goods such as furniture, electrical, and hardware items, which had been largely unavailable during the lockdown.
"This brought furniture and hardware spending to a higher level than usual, which could be due to pent-up demand because such non-essential businesses were closed during the level 4 lockdown in April," retail statistics manager Kathy Hicks said.
Spending on food and other consumables edged higher but had been the least affected by pandemic restrictions.
Overall card spending for May was $5.3 billion, which was still below pre-Covid-19 levels, and 6 percent lower than the same month last year.
An economist said the spending surge was probably driven by pent-up demand, which would probably last for some months, but recovery to last year's levels would take longer.
"That's due to factors including job losses, increases in debt, and general nervousness about the economic outlook which will dampen spending appetites. Continuing border restrictions will also be a major drag on spending in areas like hospitality," Westpac senior economist Satish Ranchhod said.
Meanwhile, major Australian electronics retailer JB Hi-Fi said it expected to take an $AU25 million write-down in the value of its New Zealand operations, which were all shut during the lockdown.
It said sales had been "solid" since the re-opening, but overall business since January has been down 19 percent on last year, and it was expecting full-year sales of about $220m.