1) Change 2) Currency 3) Decimalization 1) Decimalization 
Decimalisation is the process of converting a currency from its previous non-decimal denominations to a decimal system, i.e. a system based on one basic unit of currency and one or more sub-units, such that the number of sub-units in one basic unit is a power of 10, most commonly 100. Today, the only currencies which are in theory not decimal are ...
The process that converted stock prices from fractional pricing to pricing in decimals; that is, in increments from eighths or sixteenths of dollars to nickels (USD0.05) or pennies (USD0.01). Decimalisation and the reduction of tick sizes are not the same and are not necessarily dependent on each other.