Apart from Asda, which said usage of bags is down 98%, the big supermarket chains have yet to report on the impact of the bag tax.
Smaller stores told UTV that they have also witnessed a major decrease in the number of bags being requested.
Hendersons said they had detected a fundamental change in shopping habits within company-owned Spar stores.
Nigel Gray, of the Henderson Group, said that carrier bag issuance has dropped off by 75% or thereabouts.
He said the company had noticed "very immediate effects".
"We've also seen the purchases of our 'bag for life' increase dramatically," he added.
"So in week one, we sold more bags for life than we sold in the whole of 2012."
The downside for the firm is a small drop-off in trade as some customers without bags are buying only what they can carry loose in their arms - but that is not expected to last.
It was claimed that the new bag levy would cause confusion and that there would be upset at the tills as customers refused to pay the five pence charge.
However, the region introduced the change easily.
In Dungannon, shoppers explained to UTV how they adapted to bringing their own bags with them.
One woman said: "I just keep them in the car and a lot of the time I don't remember, so I do have to pay for them. But, I just leave them in the car now. As I say, it's just getting into the habit."
While another said: "I don't mind it so much. I think something has to be done as you see I live out in the country and there's a lot of bags chucked in the trees and things like that you know.
"So it'll be nice to see them being put to good use."
Newells supermarket has seen demand for bags drop sharply since the levy came in earlier this month.
Brenda Taylor, of Newells, told UTV: "I would say it's probably down more than half than what it was before the bag levy came in.
"The people are bringing their own bags and they're using maybe boxes, they keep the boxes apparently in the boot of the car - where they take their groceries out in their trolley or their baskets and then they transfer them into their own car."