四舍六入五成双

five2pair.php

<?php
function five2pair($number)
{
    $num_str = strval($number);
    if (!strpos($num_str, '.')) $num_str .= '.';

    list($int, $dec) = explode('.', $num_str);

    $new_num = floatval( $int . '.' . substr($dec, 0, 2) );
    if (isset($dec{2})) {
        $fen = $dec{2};

        if ($fen == 5) {
            if (strlen($dec) > 3) {
                $end_part = substr($dec, 3);
                if (intval($end_part)) {
                    $new_num = $new_num + 0.01;
                }
            } else {
                if (intval($dec{1}) % 2) {
                    $new_num = $new_num + 0.01;
                }
            }
        } elseif ($fen >= 6) {
            $new_num = $new_num + 0.01;
        }
    }

    return number_format($new_num, 2);
}