Judge Cooper said the $4000 had never been recovered.
Williams committed the robbery while on bail for a charge of burglary and while he was the subject of a supervision order.
Judge Cooper said he had read the victim impact report in which the bank teller described how frightening the incident was.
"She was very anxious about what happened but with good support she appears to be making a reasonable recovery," Judge Cooper said.
He said Williams had initially pleaded guilty to a charge of aggravated robbery but that was rightfully set aside by the Court of Appeal and a charge of robbery was laid to which Williams pleaded guilty.
Williams had numerous convictions, including 14 for dishonesty offending including burglary. Judge Cooper told Williams he was subject to the three strikes law for violent offenders.
Judge Cooper warned him that if he were convicted of another violent offence he would serve the full sentence. If Williams was convicted of murder he would serve a life sentence without parole unless the sentence would be manifestly unjust.
Williams' lawyer, Richard Barnsdale, said he had a letter of remorse written by Williams but did not give any further oral submissions in court after Judge Cooper indicated at the start of the sentencing that he would sentence Williams to three years' jail.
At the time of the incident it was reported former Kawerau police sergeant Tony Moller had to slam on his brakes to avoid Williams as he fled the bank.
Mr Moller said he was driving along Onslow St when a man ran directly into his path.
"If I hadn't slammed on my brakes I would have collected him," Mr Moller said. Mr Moller tried to chase Williams but Williams had already gone.
