LB – if you are thinking of lying for shidduchim, you must ask first and not rely on Yismach’s quote from R’ Elyashiv zts”l. First of all, there are other opinions as you can see.
Second of all, there may be conditions attached.
Third of all, you have to know what “lying slightly” means. Maybe it means if a shadchan sees an old copy of a resume of yours that says that you are 2 years younger, and you don’t correct her.
Something else to think about – personally, I don’t think I would go out with someone who lied about his age even if he was told it’s permissible. It is very important to me that the guy be honest and straightforward and that our relationship be based on honesty. So there may be others who don’t think it’s the best way to start a relationship and would not want to marry you if they found out that you lied. And even if they do, it could undermine their ability to trust you in the future. (I am talking about outright lies now, and not about evading the truth or letting someone think you are younger than you are and not correcting them before a first or second date).