function getBackgroundPositionX(value){

	if(!$(value).css('backgroundPosition')) {
		//ie fix
		backPos = $(value).css('background-position-x');
		posX = Number(backPos.split("px")[0]);
	} else {
		backPos = $(value).css('backgroundPosition').split(" ");
		posX = Number(backPos[0].split("px")[0]);
	}

	return posX;
}

$("ul li").each(function(){
	var backPos = $(this).css('backgroundPosition');
	var pos = backPos.split(" ");
	var posX = Number(pos[0].split("px")[0]);
	var posY = Number(pos[1].split("px")[0]);
	$(this).data('posX', posX);
	$(this).data('posY', posY);

	$(this).css({backgroundPosition: posX + 'px ' + posY + 'px'});
});

CSS Background position parse

jQuery