All futures contracts have a minimum price fluctuation also known as a tick. Tick sizes are set by the exchange and vary by contract instrument.
E-min S&P 500 tick
For example, the tick size of an E-Mini S&P 500 Futures Contract is equal to one quarter of an index point. Since an index point is valued at $50 for the E-Mini S&P 500, a movement of one tick would be
.25 x $50 = $12.50
NYMEX WTI Crude Oil
The tick price of a NYMEX WTI Crude Oil contract is equal to one tenth of a point, and since a point is valued at $1000, the tick price is $10. The NYMEX WTI Crude Oil contract is quoted therefore in increments of .01.
Tick sizes are defined by the exchange and vary depending on the size of the financial instrument and requirements of the marketplace. Tick sizes are set to provide optimal liquidity and tight bid-ask spreads.
The minimum price fluctuation for any CME Group contract can be found on the product specification pages.