We have a page of links to all state gaming commissions -
http://www.americancasinoguide.com/L...missions.shtml
Just click on the name of the state you are interested in and once you are on the state's site, you can usually find the slot payout percentages listed.
For Nevada the information is called a 'Gaming Revenue Report.' You can access the information on this page - gaming.nv.gov/gaming_revenue_rpt.htm