....and after looking at the code I see that you have used char Test[25]. So.....

Code:
void ConvertTest(char *input)
{
    double usDollar=0.0;
    double test=atof(input);
    printf("test = %f\n",test);
    printf("input = %s\n", input);
    printf("US Dollar Amount entered %.2f\n",test);
}
.....or something similar.

TDM