Follow the Canadian Oxford Dictionary, which is the authority for CP spelling.

• centre (not center, unless part of a proper name, usually a U.S. organization) in past tense is spelled centred
• per cent (two words, not percent or % in text)
• focused, focusing (not focussed, focussing)
• program (not programme)
• university (do not cap "U" when word stands alone)

Exceptions

• advisor (not adviser)