A key to cracking the cases was tips from people who had been offered the goods cheaply, she said.
"It appeared that cigarettes were being targeted and we know that the community is being offered them for sale. There have been cigarettes for sale on [online] forums but mainly offered to people that [the offenders] know."
The special unit was established in January after the robberies began escalating in frequency and violence - with one attendant kicked and narrowly dodging a tyre iron being swung at him.
That robbery, at Z Energy on Clevedon Rd, Papakura, remains unsolved and police are seeking information from CCTV footage that pictured the offenders clearly.
University of Canterbury criminologist Dr Greg Newbold said black market tobacco was not traditionally popular in New Zealand, but it didn't surprise him that this was occurring.
"There is always a market for cheap sources of commodities which are high in tax, any stolen commodity in fact, and tobacco would be an obvious one.
"Not that many people smoke these days but the [people who] smoke the most are in the [poorer] areas and they would be more likely to want these at cheaper prices."
Overseas, black market tobacco thrived and was often linked to organised crime, he said.
"I haven't heard it is a major thing here. People would be more interested, if they were going to make money through the black market, in selling marijuana or meth.
"But [black market tobacco] slips under the radar and the penalties are lower, so you could make quite a lot of money for relatively little risk."
Taxpayers Union spokesman Jordan Williams said the crimes were worringly similar to incidents overseas.
"This is similar to what has happened in Australia where the goods are high in excise tax."
He said the Government needed to come up with other ways to stop smoking, instead of raising taxes.
