Using locale of es_PY and Zend_Currency, was trying to get a negative currency value using precision of 0. The positive values comes out good, the problem is when the value is a negative number. The negative currency ignores precision settings.

 
$locale = new Zend_Locale('es_PY');
$currency = new Zend_Currency(array('precision' => '0'), $locale);

 
// With value of -50000, it should show ₲ -50.000
$this->currency(-50000) // ₲ -50.000.00 
// With value of 50000, it has no problem
$this->currency(50000) // ₲ 50.000

I was able to do a quick fix and get the result I wanted by commenting out a line in Zend_Locale_Format. It is not a fix, as I do not know whether the change I made breaks anything else. I am not a "pro" in programming, just 3-4 years of experience with it. Thought I'd report this as it was bugging me for a while.

This is the original code from Zend_Locale_Format starting on line 417:

 
        if ($options['precision'] == '0') {
            if (iconv_strrpos($format, '-') != 0) {
                $format = iconv_substr($format, 0, $point);
                        . iconv_substr($format, iconv_strrpos($format, '#') + 2);
            } else {
                $format = iconv_substr($format, 0, $point);
            }
        } else {
            $format = iconv_substr($format, 0, $point) . $symbols['decimal']
                               . iconv_substr($prec, 2);
        }

The change I made was to comment out the concatenation on line 420.

 
        if ($options['precision'] == '0') {
            if (iconv_strrpos($format, '-') != 0) {
                $format = iconv_substr($format, 0, $point);
                        // TODO: Make the quickfix a proper fix.
                        // The below portion was concatonated with the statement above
                        //. iconv_substr($format, iconv_strrpos($format, '#') + 2);
            } else {
                $format = iconv_substr($format, 0, $point);
            }
        } else {
            $format = iconv_substr($format, 0, $point) . $symbols['decimal']
                               . iconv_substr($prec, 2);
        }