Hannah, of Christchurch, either altered or deleted the cash receipt so it was not entered into the accounting system.
She then kept the cash, which totalled $16,225.
When her offending was uncovered, she admitted the thefts.
She told police she "had a lot of bills to pay".
Hannah, who has no previous convictions, left the company in November 2013.
Today she pleaded guilty to a representative charge of theft by person in special relationship.
Judge Tony Couch said it was a serious breach of trust.
Police are seeking a reparation order for the stolen cash, plus another $5261.26 to cover the company's cost of an accountant to identify the offending.
Judge Couch referred the matter for a restorative justice conference between Hannah and her former employers ahead of sentencing on December 9.
Her bail conditions were altered today to allow her to travel to Australia for a family wedding.