A robber threatened to a stab a 74-year-old shop worker before stealing a charity box from a newsagents in Leeds.
Amelia Ross was locked up for 33 months after a court heard how the victim had quit her job because she had been left too frightened to work at the shop in Morley.
Leeds Crown Court heard the 23-year-old targeted Fountain Street News on April 11 last year.
Susan Evans, prosecuting, said Ross approached the till to pay for shopping.
As she was being handed change by the shop owner she took out a knife and demanded money.
The 74-year-old member of staff was at the same side of the counter as Ross at the time.
The defendant threatened to hurt the woman if she was not given any money.
The shop owner refused to hand over cash and Ross picked up a charity box before leaving.
Miss Evans said Ross discarded some of her clothing as she left the shop.
The clothing was recovered and found to contain her DNA.
She was also identified from CCTV footage of the incident.
Ross, of Marshall Close, Morley, pleaded guilty to robbery and possession of an offensive weapon.
Nicholas Hammond, mitigating, said the offence was carried out to fund her drug habit.
Mr Hammond said Ross was under the influence of cocaine at the time.
The lawyer told the court Ross had began taking drugs after forming a relationship with a man who had a drug addiction.
Mr Hammond said Ross was now receiving help to tackle her drug problem.
Judge Simon Phillips QC said: "It is something of a personal tragedy to see a woman of 23 years of age before the court for the first time
"One of the consequences of the offending is that (the victim) has now chosen to cease her employment because it has affected her.
"You ran off with a charity box.
"The contents were unknown, but no doubt you realise what a mean act that was."