Looks to be too straight for a die crack. They are usually irregular lines. Might of been struck through some debris. Reverse shows possibly some debris. I do not like to use the word grease. It could be many diff. things beside just grease.
It is a small delamination. No added value, laminations/delaminations are fairly common on nickel alloy coins. A large delamination, one where a significant portion of a face was missing, would garner a modest premium.
I think you would get more than 5 cents...how much....I would guess a dollar (which is a guess and not based off of anything)...but who knows on eBay if a few people get in a bidding war...
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