Function to show original non-sale price in WooCommerce cart.

WooSalesPrice_functions.php

<?php
// Do not copy opening PHP tag

// Show non sale product price in cart
add_filter( 'woocommerce_cart_item_price', 'wsm_show_nonsale_price', 10, 2 );
function wsm_show_nonsale_price( $newprice, $product ) {
	$_product = $product['data'];
	$saleprice = $_product->sale_price;
	if ( $saleprice > 0 ) {
		$newprice = '';
		$newprice .= '<del><small style="color:#c9c9c9;">';
		$newprice .= woocommerce_price( $_product->regular_price );
		$newprice .= '</small></del> <strong>';
		$newprice .= woocommerce_price( $_product->sale_price );
		$newprice .= '</strong>';
			
		return $newprice;
	}
	
	else {
		$newprice = woocommerce_price( $_product->price );
		return $newprice;
	}
}