Nicole Amy Kelly pleaded guilty in the ACT Supreme Court to 35 fraud charges after misusing three credit cards left by customers at her workplace last year.

The court heard Kelly took five credit cards which had been accidentally left by shoppers at the Tuggeranong Hyperdome chemist where she worked.

Between August and October, she used three of the cards to make $1380 of purchases online and at the Tuggeranong mall.

Most of the items were of low value, including books, a poster, clothing and headphones.

The theft came to light when Kelly turned herself into police and confessed to the offences.

The 21-year-old handed the items to officers.

She has since repaid the full cost of the purchases to the three banks which issued the cards.

The court heard Kelly has since been diagnosed with bipolar disorder.

A pre-sentence report said she may have been suffering a manic episode, which can cause poor judgment and impulsive behaviour, at the time of the spree and the actions were not consistent with her previous behaviour.

The report said Kelly posed a low risk of reoffending.

Justice Hilary Penfold said the student's admissions to police, her early guilty plea and clean record entitled her to leniency. She said a prison term was unnecessary.

The judge recorded convictions to 24 counts of obtaining property by deception and 11 charges of dishonestly obtaining a financial advantage.

Justice Penfold ordered Kelly to perform 105 hours of community service, pay a $500 security and sign a 12-month good behaviour bond.

The judge warned that a breach of the good behaviour bond or failure to perform the community service could result in resentencing in all 35 matters.

Justice Penfold imposed no supervision, rehabilitation or counselling conditions but warned Kelly to seek help immediately if her illness flared up. ''Don't fall into a dangerous mental state again,'' she said..