Why is the output not what is expected?

This code is supposed to take the amount due for an item and the amount paid. Then find the change in coins and dollars. When ever I put due: 41.35 and received: 50.00, I get 8 dollars, 2 quarters, 1, dime, 0 nickels, 4 pennies. In reality, it should be 8 dollars, 2 quarters, 1, dime, 1 nickel, 0 pennies.

import java.util.Scanner;
public class Cashier {
private double amountDue;
private double amountReceived;
private int dollars = 0;
private int quarters = 0;
private int dimes = 0;
private int nickels = 0;
private int pennies = 0;
private double toConvert;
public Cashier(double due, double received){
amountDue = due;
amountReceived = received;
toConvert = received - due;
}
public int getDollars(){
dollars = (int)toConvert;
toConvert -= dollars;
return dollars;
}
public int getQuarters(){
quarters = (int)(toConvert/.25);
toConvert -= (.25 * quarters);
return quarters;
}
public int getDimes(){
dimes = (int)(toConvert/0.1);
toConvert -= (.1 * dimes);
return dimes;
}
public int getNickels(){
nickels = (int)(toConvert/0.05);
toConvert -= (0.05 * nickels);
return nickels;
}
public int getPennies(){
pennies = (int)(toConvert/0.01);
toConvert -= (0.01 * pennies);
return pennies;
}
public static void main(String[] args){
Scanner ask = new Scanner(System.in);
System.out.print("Enter Amount Due: ");
double amtDue = ask.nextDouble();
System.out.print("Enter Amount Received: ");
double amtReceived = ask.nextDouble();
Cashier one = new Cashier(amtDue, amtReceived);
System.out.println("Dollars = " + one.getDollars());
System.out.println("Quarters = " + one.getQuarters());
System.out.println("Dimes = " + one.getDimes());
System.out.println("Nickels = " + one.getNickels());
System.out.println("Pennies = " + one.getPennies());
}
}

Interesting problem you ran into here. Here's how I went about figuring it out. First thing I did was try printing the amount of change left to break down after you ran each function. I changed the main function to look like this:

NOTE: I had to change toConvert to static to use it in the main function

public static void main(String[] args) {
Scanner ask = new Scanner(System.in);
System.out.print("Enter Amount Due: ");
double amtDue = ask.nextDouble();
System.out.print("Enter Amount Received: ");
double amtReceived = ask.nextDouble();
TestA one = new TestA(amtDue, amtReceived);
System.out.println("change due: " + toConvert);
System.out.println("Dollars = " + one.getDollars());
System.out.println("change due: " + toConvert);
System.out.println("Quarters = " + one.getQuarters());
System.out.println("change due: " + toConvert);
System.out.println("Dimes = " + one.getDimes());
System.out.println("change due: " + toConvert);
System.out.println("Nickels = " + one.getNickels());
System.out.println("change due: " + toConvert);
System.out.println("Pennies = " + one.getPennies());
System.out.println("change due: " + toConvert);
}

The output looked like this:

Enter Amount Due: 41.35
Enter Amount Received: 50.00
change: 8.649999999999999
Dollars = 8
change: 0.6499999999999986
Quarters = 2
change: 0.14999999999999858
Dimes = 1
change: 0.04999999999999857
Nickels = 0
change: 0.04999999999999857
Pennies = 4
change: 0.009999999999998573

This told me that the issue was in rounding your double values. The change should have been 8.65 in the first part if the program was running correctly. This has to do with how double values are stored on the hardware and its a pretty confusing topic(to me, at least).

Change the values to float instead of double and it'll work fine. There's info out there on this website and others about rounding double values and there are ways around it like formatting to x number of decimals and rounding and such but think changing it to float is an easier avenue.

You need to designate the input in terms of cents, which is the smallest form of currency you can accept. Otherwise, for a charge of 70¢, given 3 quarters, your code would try to it convert it to dollars.

The code is very simple, and can be written as a single recursive function without the need for dozens of special methods. I won't do it for you, but the following should give you a very good idea.

865 / 100 = 8
65 / 25 = 2
15 / 10 = 1
5 / 5 = 1
0 / 1 = 0

After this step : toConvert = received - due;
The toConvert amount turns to 8.649999999999999
This requires an additional step to the round of decimal to two places so the amount turns 8.65
change your Cashier funtion to this:

public Cashier(double due, double received){
amountDue = due;
amountReceived = received;
double num = received - due;
toConvert = Math.round(num * 100.0) / 100.0;
System.out.println(toConvert);
}

This solution works temporary while working with a double. But converting figure to cents and using arithmetic solve is the right way.