No, you need Expertise to be at exactly 7.5% to effectively be capped. That's 761 Expertise in rating, if I'm not mistaken, someone correct me if I'm wrong.
And before you ask, yes, Hit needs the same amount of Hit-rating to be capped. 761 Hit or 7.5%.
It's 2550 rating for level 90, which grants you 7.5% reduction to being parried and dodged, the expertise hard cap is 15% (the actual parry cap), but as bosses and mobs can only parry from the front - and you would be well advised to attack from behind, that should not be a problem.
Your attacks can only be parried if you stand in front of a target.
As a melee dps you should always (Unless the fight doesn't let you) be behind your target, therefore your attacks can not be parried hence why having 15% expertise is pointless.
Only get 7.5% expertise, this means your attacks can no longer be dodged when attacking from behind, this is what is important.