This isn't an issue with C++ libraries specifically, that's simply how the console works; user input + enter creates a newline. You have to use a custom console library (such as Curses).
#include <iostream>
int main()
{
int x;
std::cout << "Enter your amount of money: ";
std::cin >> x;
std::cout << "\n$" << x <<" dollars.\n";
}
Enter your amount of money: 125
$125 dollars.
You could refine the variable to be a float/double so you can enter dollars and cents, and improve the output to show two decimal places even when there aren't two.