c语言计算绝对值的题目中为什么输入99.99会输出99.98，输入9.9输出9.89

Question

#include<stdio.h>int main(void){float a,b;int c;while(scanf("%f",&a)!=EOF){ b=(int)(a*100)/100.00;    if(a>=0)printf("%.2f\n",b);if(a<0)printf("%.2f\n",b*(-1));}return 0;}