isidoro_mtnez on "[Plugin: Postcode Shipping Rates- WooCommerce] Paypal rounding"

So it definitely is a localization problem. I've changed comma values with dot values in my db, and everything works right. WooCommerce solves it by calling "wc_format_decimal" function (inside "wc-formatting-functions.php"), wich takes localized comma separator into account, before saving that pricing values into database.
Maybe this function could be used in postcode shipping.