The five were arrested in the southern central parts of Sri Lanka where they allegedly had been hiding after committing the offence on December 28, the Lankadeepa newspaper said.
All five suspects were in possession of guns or hand grenades at the time of their arrest over the past three days, the paper quoted police as saying.
At least 10 men armed with sophisticated weapons broke into the tourist resort at Hungama, in Tangalle, 150 kilometres south of the capital, in the early hours and killed the owner after failing to get him to open the hotel's safe.
The German, Ulrich Haupt, 38, who was manager of the Darwin holiday resort, was shot twice. He succumbed to his injuries later apparently due to a delay in taking him to hospital.
A Sri Lankan-born German woman who had been a guest at the hotel was raped by three of the armed men.
The gang robbed and then tied up at least six other tourists before escaping.
Police were quoted as saying that the five arrested suspects have been placed in custody under a detention order under existing emergency regulations.
(dpa)