why is my code wrong?

Question

I am unsure why it is not giving me the output that I want because when I look at this to me it should work. If I posted too much code then tell me and I will take it down but I tried to limit it so it wouldn't go against the academic honesty. I have the code that prompts the user for input which I have saved in variable change. If you would like to see all of my code then let me know. I am new to coding but this pset1 has taken WAY too long for me to complete I struggled with mario too. So I don't know if it's just the way I am going about attacking the problem or what but any help would be greatly appreciated! Thanks in advanced.

EDIT so I have edited some of my code and I am displaying all of my code BUT it's not working still. I think that the reason has something to do with when I round? Or maybe the fact that I am using Do While loops? The problem is when I input .01 it gives out 4 and if I do 4.2 it gives out 7.

#include <stdio.h>
#include <cs50.h>
#include <math.h>

int main(void)
{
    float change;
do
{
    printf("How much change is owed?\n");
    change = GetFloat();
}
while(change <= 0);

change = roundf(change * .20);

float Q = .25;
int count = 0;
do
{
    change -= Q;
    count++;
}
while(change >= Q);
float D = .10;
do
{
    change -= D;
    count++;
}
while(change >= D);
float N = .5;
do
{
    change -= N;
    count++;
}
while(change >= N);
float P = .01;
do
{
    change -= P;
    count++;   
}
while(change >= P);
printf("%d\n", count);
}

Answer 1

You multiplied the change by 100, converting them to pennies so if i have 0.10 changes left that will mean 10 pennies, but then you used Q = 0.25, D = 0.1 and so on, so they are not converted to pennies too.

I think that is not correct, don't you agree?

Answer 2

After doing round off and making pennies into dollar(or simmilar) you should divide them with the same quantity ... not by something like .5 or .25

hope you got what i want to point at you.