The next day, police showed Ms Howell CCTV footage of her Woolworths trip and told her she had been accused of taking "about A$1000" (NZ$1082) too much.
She was charged with dishonestly deceiving another to benefit herself.
But Ms Howell told the Advertiser she was determined to fight the charges, even though she would likely rack up a A$12,000 (NZ$12,988) legal bill in the process.
"I've always prided myself on being honest and I'd never put my job or reputation at risk," she told the publication.
"I understand the lawyer's advice, that it would be faster and more cost-effective to plead guilty, ask for no conviction and get it over with — but my conscience won't let me do that.
"I am exhausted, I put my trust in Woolworths to do the right thing and I feel they've let me down."
Ms Howell said the drama could have been avoided if staff had informed her of the mix-up from the beginning.
"I was (at Woolworths) later that night and the next day, they know me as a regular so I don't know why they didn't just say, 'Our till was down and we think you might have it'," she told the Advertiser.
"I would've happily repaid it and I still would — but I haven't been given a chance."
Ms Howell told the publication she was worried the incident could damage her nursing career, and described the situation as a bad dream.
A Woolworths spokeswoman told the Advertiser police were contacted following an internal investigation.
The matter will return to Mt Gambier Magistrates Court for a pre-trial conference later this month.