How much would I get taxed on lottery winnings if I write some big gift checks?

I live in Minnesota, was wondering what would happen taxwise if I win the Powerball and I have $75 million in cash after tax and I wanted to write checks for $1-2 million each to six family members plus I'd want to buy a million dollar house for my Mom, a condo close to $2 million for my Dad and a house for my inlaws around 1.5 million. What are the laws and how much tax would I get hit with?