Consider member prices a "sale" so regular price is shown with a strikethrough with WooCommerce and PMPro WooCommerce

my_pmprowoo_woocommerce_product_is_on_sale.php

/**
 * Consider member prices a "sale" so regular price is shown with a strikethrough
 * If PMPro WooCommerce is active and setup to discount prices,
 * then the calls to $product->get_price() will be filtered to return
 * the member price.
 *
 * Add this code to a custom plugin.
 */
function my_pmprowoo_woocommerce_product_is_on_sale( $on_sale, $product ) {
	$regular_price = (float) $product->get_regular_price();
	$member_price = (float) $product->get_price();

	if( $regular_price > $member_price ) {
		$on_sale = true;
	} else {
		$on_sale = false;
	}

	return $on_sale;
}
add_filter( 'woocommerce_product_is_on_sale', 'my_pmprowoo_woocommerce_product_is_on_sale', 5, 2 );

/** 
 * Hide the "Sale!" tag on some products that have a lower member price, but aren't really on sale.
 * Feel free to tweak the code below to fit your needs.
 */
function my_pmprowoo_woocommerce_sale_flash( $sale_flash, $post, $product ) {
	// remove sale flash if the "sale" price is greater than the regular price
	if( (float) $product->get_price() > (float) $product->get_regular_price() ) {
		$sale_flash = '';
	}

	// if the product didn't have a "sale" price set, hide the tag
	if( $product->get_sale_price() === '' ) {
		$sale_flash = '';
	}

	return $sale_flash;
}
add_filter( 'woocommerce_sale_flash', 'my_pmprowoo_woocommerce_sale_flash', 10, 3 );