I've attempted to add the strike by doing the following:
I edited the frontend_default.css in Hikashop.
Found this:
span.hikashop_product_price, .hikashop_checkout_cart_additional, .hikashop_checkout_cart_payment, .hikashop_checkout_cart_coupon, .hikashop_checkout_cart_additional {
color: #2C8296;
font-size: 14px;
font-style: italic;
font-weight: bold;
font-family: "Times New Roman",Times,serif;
white-space: nowrap;
I added "text-decoration: line-through;" at the end of this code. This put a strike through both prices. I have been messing with it since and cannot figure this out.