If you want to be able to show information about relevant discounts or format your price to convey some sort of information, you will need the help of a pricing formatter. Here are some common ones.

• Commerce Price FlexyFormatter allows you to display price broken down by components as well as tax information and up to two strikethrough prices that can show savings or discount information.
• Commerce Price Extra Formatters (Commerce Module Tuesday) currently provides 3 additional formatters. RRP / Your Price shows the regular retail price and the price the user pays. Formatted Price with Prefix and Suffix lets you present a price with text before and after (e.g. "only £9.99 for a limited time only"). Formatted Price with no decimal places displays prices for integer-priced products without decimals.
• Commerce Price Savings Formatters (Commerce Module Tuesday) shows the amount you save if a discount is applied.
• Commerce Price Decimals Formatters lets you specify the number of decimal points that prices will use.
• Commerce Price Components lets you choose which components are reflected the rendered price. Useful for views.
• Commerce Price History provides a chart for showing the price of a product over time.
• Commerce Price Extra does a couple of things: it allows ordering of price components in checkout cart pane and for the discount to be printed on its own line. You may want to check out the patch to merge it into Commerce Extra Price Formatters.