Green’s Dictionary of Slang

a shop assistant who steals from the shop till.

1864, 1867, 1870

Hotten Sl. Dict.

(UK Und.) an act of theft from a shop till; thus till-diver, one who carries out such a theft.

1703		Hell Upon Earth 4: Some are expert at Till-Diving; which is going into a Shop with pretence to buy something and with several Excuses [...] to make the Shop-keeper turn his back often, they put a small Whale-Bone, dawb’d at the end with Bird-Lime, into the Till.
1708		J. Hall Memoirs (1714) 5: Till-Divers, Such as go into Shops with pretence to buy something, and with several Excuses of seeing this Thing and that Thing, to make the Shopkeeper turn his Back often, they put a small Whalebone, daub’d at the End with Bird-lime, into the Till of the Counter, and draw up money; but this Employment is now grown something out of Date.

(UK Und.) a person who steals from a shop cash register.

1856		H. Mayhew Great World of London I 46: ‘Till friskers,’ who make off with the contents of tills.
1861		H. Mayhew London Labour and London Poor IV 25: ‘Till Friskers,’ or those who empty tills of their contents during the absence of the shopmen.
1882		Sydney Sl. Dict. (2 edn) 8: Till Friskers - Robbers of tills.
1910		Eve. Star (Wash., DC) 13 Feb. 12/3: ‘Anyone could see he wa’n’t one of your strong arms or till friskers’.

(UK Und.) the robbery of a shop cash register; also attrib.

1899

C. Rook Hooligan Nights 96: His last exploit in the till-lifting line.

(Aus. und.) the robbery of a shop cash register;.

1886		Eve. News (Sydney) 27 Apr. 7/3: I immediately began operations by going ‘till sneaking.’ I stole several tills the first day.
1902		‘The Wasp’ ‘Tales of the Penance Track’ in Bulletin (Sydney) 31 May 31/2: ‘[J]apanning,’ known to the initiated as cash-box or till-snatching.

theft from a cash register.

1970

J. Wambaugh New Centurions 33: I‘m always seeing his name on robbery, burglary, or till tap reports.

(US Und.) one who steals from a cash register, esp. when employed as the cashier.

1848		N.Y. Herald 9 Jan. 3/1: That notorious ‘Till Tapper’ called Charley Hayden, was arrested yesterday.
1861		N.E. Police Gaz. (Boston, MA) 12 Oct. 8/2: Her new $7 bonnet [was] destroyed. Her till tapper must come down with another .
1882		A. Trumble Crooked Life in Nat. Police Gaz. 10 June 6/2: Till tappers operate in gangs of three or four [...] one of the ‘tappers’ walks in [to a store] and begins pricing things. Another follows [etc].
1897		Eldridge & Watts Our Rival, the Rascal 141: [I]n his prime he was [...] an expert ‘till-tapper.’ This latter distinction marks the sneak thieves who make a specialty of infesting stores and offices, with the design of stealing behind a counter or rail and filching from tills or money drawers while their confederates are distracting the attention of the cashiers and clerks.
1903		N.Y. Times 7 Oct. 8: Their rank [among criminals] will be about that of tilltappers and pickpockets [DA].
1927		H. Asbury Gangs of N.Y. 233: The members of this outfit were for the most part till-tappers and cheap sneak thieves.
1949		N. Algren Man with the Golden Arm 197: Catamites and sodomites, bucket workers and bail jumpers, till tappers and assistant pickpockets.
1969		‘Iceberg Slim’ Pimp 120: You a ‘till tapper’ or maybe a burglar, huh?
1999		E. Bunker Mr Blue 110: There were also ‘till tappers’ and a few burglars.

(US Und.) the robbery of shop cash registers.

1840

N.Y. Daily Express 20 Nov. 2/7: Robbing Store Tills. [...] Among thieves this feat is termed in their flash dialect till-tilting.

to rob a shop till.

1862

Morn. Post 18 Dec. 3/3: No sneaking prig to draw a till, Or o’er a pocket potter.