A receipt was a document confirming a certain payment or delivery had been received.
In 2369, Quark, who had recently become Grand Nagus, sent away petitioners and headed over to Quark's to check the receipts. (DS9: "The Nagus")
In 2370, Sakonna visited Quark's and identified Quark as the proprietor as he was counting his receipts. (DS9: "The Maquis, Part I")
In 2372, Quark went over his receipts of a day, which were pretty low due to the Bajoran Time of Cleansing. (DS9: "Bar Association")
In 2375, when Nog was living with Vic Fontaine in the holosuite for a time, he played Vic's accountant and was working on the receipts of 1961 when Ezri Dax visited. (DS9: "It's Only a Paper Moon")
Later that year, Brunt asked Quark to sign a receipt for a bribe of sixty bricks of latinum, as bribes were now tax deductible. (DS9: "The Dogs of War")