Twitter user Justin Hourigan shared a picture of the display in the Tralee branch, which was mocked as the "choclamation".
But while some people said it could help make Irish history accessible to children, others believe it is disrespectful and fear the centenary commemorations next year will become "overly commercialised".
James Connolly Heron, great-grandson of 1916 leader James Connolly, said: "There's so much more we can tell about the 1916 leaders than reducing them down to covering a chocolate bar."
He told RTE's Liveline it was important to educate younger generations about the Rising, but said the bar was "simply a commercial venture".
"One would expect a certain amount of sensitivity particularly around those that were executed," he said.
Fianna Fáil Wexford councillor Malcolm Byrne, who initially raised concerns about the bar, said the centenary must not be "overly commercialised".
Heatons has not responded to a request for a comment.