I would also make a interface of these methods as well something like this:


    interface investmentCompound
    {
    	double getQuarters(double numOfQuarters);	
    	double getDimes(double numOfDimes);
    	double getNickles(double numOfNickles);
        double performCalculations();
        double formatPrice(double priceToFormat);
        ...
    
    }

 - The above will give your class a much better design and help you better code as well. Always program in a way that when anyone reads your code, the method and variable names are self-explainatory on what your class is doing.

 - Give your `main()` function the minimal capability to just call methods and variables instead of declaring everything there

 - In realworld, you will always have a API i.e. getters and setters and methods like how I mentioned in the interface above so this will give you better practice so when someone wants to call your code, they should be able to use the methods.

 - Since you are going to use  `numOfNickles,numOfQuarters, numOfDimes` variable names several times, its best to declare that at class level so declare them as class variables instead of `main()`