The woman told the worker that she had a stillborn son a year ago, and as a tribute to him, she wanted to pay for someone else's cake.
The worker found an order for a 1-year-old's cake, so the woman paid for it in full.
The employee posted the receipt on Facebook, saying he hopes the woman finds peace through this touching tribute.
"It was probably one of the most touching things I've seen in all my years working in retail. I hope that this lady finds peace through this tribute and that the customer receiving this gift will, if nothing else, pay it forward," he wrote in the Facebook post.