With originally around $50 worth of products, the elderly lady proceeded to take items out of her trolley, though her card declined again. She was starting to get a bit flustered by the line forming behind her and got her pin number wrong, Ms Mclean said.
"She was getting quite upset about it so I just handed her my [Eftpos] card," she said.
Though the total was only $17.30, the elderly woman was obviously touched by the gesture. "And then she gave me a hug," Ms Mclean said.
"Afterwards I just felt really good," she said. "I just was really happy that I had put a smile on someone's face."
The elderly woman was very genuine and the items in her trolley were obviously essentials, Ms Mclean said.
"I remember thinking that it's things you would need."
Ms Mclean had no plans to tell her bosses about the gesture as she was worried she would get in trouble because technically she was serving herself. On the contrary, they were very happy and the editorial now hangs in the office.
"They just said 'good on you' and 'well done for helping out an elderly person'," Ms Mclean said.
She had no idea it was in the paper until a customer told her about it and friends tagged her in the post on Facebook. The story was shared 594 times on Facebook with lots of people praising Ms Mclean.
"It's wonderful to hear such a positive story and also realise that there are still some caring people out there," wrote Cherie Aplin.
"Well done young lady, what a beautiful heart you have," wrote Leigh Williams.
The public response was out of the blue, Ms Mclean said.
"I wasn't really expecting this at all."