She formally handed over the letters to the nurses in a symbolic gesture at a function at the Secretariat, an official release said.
The five were among 7,243 nurses who passed the exam.
A total of 40,465 candidates had taken the examination.
Finance Minister O Panneerselvam, Health and Family Welfare Minister C Vijaya Baskar and Chief Secretary K Gnanadesikan were among those who took part in the event.