We have been living together for almost 5 years (6 at the time of the wedding) at this point and we have everything we need so we don't need gifts. Would it be tacky to request in lieu of gifts we would like help with the Honeymoon fund?
Edit: Thanks guys for all your answers! We will just not register for gifts as we do not need anything. We did not want to be uncouth but did not know what the best course of action would be for us. We have attended other weddings that have done the same and we didn't think twice about it. His Mother disagrees completely and thinks we would still have a registry.