Easy bucks. The second argument of your round function is 3.1, so it returns a multiple of 3.1, which happens to be 99.2, because that is as close as you can get from 100.

这是啥程序，帮顶

The case I can think of is that you have customized formats like the example below,

proc format;
value pct
0-<99 = best.
99-100=100
;
run;

data t1;
  colpercent=99.2;
  call symputx('pct',colpercent);
  format colpercent pct.;
  run;

  proc print;run;

  %put >>>&pct<<<;

do a proc contents and take a look there is a format for  the variable.

你把你的数据集上传上来才比较方便看原因吧，因为显示的100可能是99.2

确实问题在此.
整数ROUND时要小心.