The amounts Nielsen stole were not large – reparation of $827 was ordered – but Judge Rea said it was not so much a question of what he took but the fact that he persisted in doing it.
"You keep on offending and offending," he said. "You are a danger to local retailers and have been for quite some time."
A probation officer's report expressed "very little faith" that Nielsen would change.
Defence counsel Will Hawkins said Nielsen had been fending for himself since a "catastrophic breakdown" in his family when he was 14. He had lived at 40 different addresses and been in and out of prison since.
Nielsen accepted prison was the "inevitable outcome", Hawkins said.
Judge Rea jailed Nielsen for 10 months, with conditions on release to not drink alcohol or take illicit drugs, and to undergo assessments for counselling and alcohol and drug treatment.
The court was told that Nielsen had been in custody since March 10, which will count towards his sentence, meaning he can expect to be released in August.