Nationally, month-to-month home price increases have been relatively steady for the past year, rising in a range of 0.1 percent to 0.3 percent since March 2012, the data agency said.
For May, the largest price increase was reported by Calgary, Alberta, where the price of new homes rose 0.9 percent.
Builders said higher labor and material costs contributed to the increase in Calgary.
New home prices rose 0.6 percent in St. Catharines–Niagara and the combined region of Sudbury and Thunder Bay in Ontario.
Winnipeg, Manitoba, also saw new home prices rise above the national average with prices up 0.5 percent in May.
Builders in Winnipeg reported higher construction costs for new homes sold that were not completed, the increase due to a new sales tax in the province that comes into effect in July and will affect homes still under construction.