The woman shared her experience on TikTok, claiming the same groceries were scanned at different amounts when she went through two registers.
"Do you use the Woolworths self-serve scanners? I have a story," she began the video.
The shopper went on to explain she needed a machine that would take cash but none were available.
At her request, a worker opened a till that had a "checkout closed" sign on it.
"There was probably a reason for that," she teased.
She scanned her small amount of groceries, which totalled $7.45 but when she went to pay a technical error arose.
"Then I call over the man, ask him to help me out here, I can't pay. There was a machine next to me, so I said why don't I just use this machine next to me? No big deal."
Moving to the adjacent register, she began putting through her items for the second time but to her surprise they scanned at a higher price.
"It came back at $7.50," she said, adding she wasn't worried about paying five cents extra but was bothered that this may have happened to other shoppers on a bigger scale.
"What I'm saying is, how many people aren't aware that this actually happens?" she asked.
"And yeah, there's probably swings and roundabouts where people are paying more or they're paying less over the span of a full shop. But how much is Woolies actually making from that? I'm very curious."
One TikTok user confirmed she was right to raise concerns.
"This has happened to me; the first machine I used froze at $190, so I moved to the next machine and it came to $170," the shopper commented.
The customer wondered whether it was an issue calibrating weight scales for fresh produce on different registers, resulting in items measuring varying amounts.
A number of supermarket workers chimed in, clarifying that the scales are checked on a regular bases however one person suggested it could have been an older model that needed servicing.
"The scales sometimes fall out of calibration over time and need to be serviced and re-calibrated, not all the scales are the same, some are old models," he wrote.
In a statement to Yahoo News, a spokesperson for Woolworths confirmed the registers are checked daily.
"We are committed to ensuring the accuracy of all trade measurement scales across our stores in line with strict regulations and test our checkout scales daily," the statement read.
"We strongly encourage this customer to reach out to our customer care team or the store directly, in order for us to investigate the items in the transaction and see what has caused the discrepancy."
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