"It has emerged that many of them did and the matters were forgotten about," the source added.
However a number of weeks ago, senior officers discovered what was happening and the garda has since been questioned about his activities.
It is understood that the traffic garda had been doing this for less than two months before his transfer.
Garda management has yet to decide what to do about his alleged activities. For the moment, the garda is not involved in frontline policing.
He has not been suspended from duty.
However as the investigation intensifies, it is possible that the garda could face serious disciplinary action, including the sack.
A source explained: "This could be the end of his career but what stands in his favour is that there is no suggestion he kept any of the money for himself: it all went to charity.
"He had an unblemished and excellent record, so it is a real shame that he has been caught up in something so stupid.
"He is well regarded by his colleagues, who can't understand why he got involved in something like this."
The charity event in which the garda was involved took place last month.