It basically means that what you're asking for would make your share too large.
aka asking for 2 nickels per 1 dime
person 1: "So what percentage would I be taking?"
person 2: "I'd give you seven, we could shake and make it happen"
person 1: "I wasn't born this morning, eighteen would be just fine"
person 2: "Why not just go ahead and ask for nickels on the dime?"
person 1: "Fifteen"
person 2: "I'd do eight"
person 1: "twelve"
person 2: "seven"
person 1: "ugh fine, 10?"
person 2: "nine it is then"
person 1: "...deal"
A word used in reference to marijuana which is also known as weed. Origin: Came from the various denominations of weed, 5 dollars worth of weed and 10 dollars worth of it which gave rise to the term nickels and dimes.