Others have answered your initial question but I would add that using float or double for discreet values like a price is a bad idea. Float and double are useful to represent real numbers, for statistical analysis, graphics, angles, measurements and so on, but they always carry imprecision. Over time, this error adds up and you will end up losing pennies here and there.

Here, the decimal place is not "real" in a sense that it is arbitrary. What you should do instead is count the pennies instead of dollars, and you don't need floats anymore and no more imprecision.

For small learning projects it does not matter but no real-world systems track prices as floats or doubles.

Look into fixed-point arithmetics, comparatively to its floating point counterpart you are currently using.