This is a completely legitimate concern but it isn't about floating point. You could be getting integer readings from your sensor and you would have exactly the same concern. In such cases you need to provide tolerances in your code that correspond to the tolerances of your measurement. You might need to implement hysteresis, you might need to take multiple samples and track moving averages, you might need to take empirical measurements of the variance you expect and suppress readings below a threshold. It is very rare however for the solution to just be to say two values compare equal if they are within a billionth part from the other.