adjust-decimal-precision.scss

@function adjust_decimal_precision($f, $v, $p: 0) {
    $n : if(0>=$p, 1, 10);
    
    @while ($p > 1) {
        $n: 10*10;
        $p: $p - 1;
    }
    
    @if 'percentage' == $f { @return round(percentage($v) * $n) / $n; }
    @else if 'round' == $f { @return round($v * $n) / $n; }
    @else if  'ceil' == $f { @return ceil($v * $n) / $n; }
    @else if 'floor' == $f { @return floor($v * $n) / $n; }
    
    @return $v;
}

test.scss

// sass test.scss:test.css --precision 3

@import 'adjust-decimal-precision';

@debug adjust_decimal_precision(percentage, (1/12), 2); // 8.33%
@debug adjust_decimal_precision(round, 8.3333%); // 8%
@debug adjust_decimal_precision(ceil, 8.3333%, 2); // 8.34%
@debug adjust_decimal_precision(null, 8.3333%, 1); // 8.333%