I work at a health care company in the US and I've seen many tattoos but they were only because they were sticking out of shirts (such as lower neck that was just above shirt when not wearing a collar) and not covered fully by the shoes they were wearing. Nobody really knows if others have tattoos because they aren't shown.

Bottom line is that tech is more than just laid back startups but there are more formal companies too. If you get something make sure it can be covered up easily as not everybody is as open to tattoos and some companies have policies about them as well.