Square Root Function not working

[bludstayne]

Why isn't this working? I always get a value that's too high. 4 would give me the correct value, but 9 up always goes over. It's kind of weird too, every perfect square makes it go over a little less, you can check it out and see what I mean.

float sqrt(unsigned int tar, float accr)
{
    float i;
    for (i=0.0f;i<tar;i+=accr)
    {
        if (i*i >= tar)
            return i;
    }
}