Can I Simply state that "A percentage of all sales will be donated to charity?"?

I am a For-Profit, raising money for an NGO. --- New York Law

It may look like flim-flam if you don't state a specific percentage. I can't say whether there is any documentation backup required for such claims.

The Federal Trade Commission probably would be watching for honest representation, I tried a search that might include relevant cases.:
search.ftc.gov/search?utf8=%E2%9C%9...

The more common case is charity taking out an excessive percentage of donations for "operating costs"

Records to maintain for tax write-offs.
smallbusiness.chron.com/tax-deducti...
www.brighthub.com/office/home/artic...