Nope. It's never okay to ask for gifts, monetary or otherwise. It is expected that people will bring gifts to a wedding but it is by no means a requirement. Similarly, you should not indicate where you are registered for gifts on the invitation either. That information (as well as the preference for cash) is supposed to be just spread by word of mouth. When a couple doesnt register for gifts, that is generally the biggest hint that they are hoping for cash instead of gifts.

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Yahoo!