I need the listings to show the currency (USD), currently they show the price, but do not indicate the exchange currency.

Currently you can do something like this with custom CSS

Listings slider

.sr-listing-slider-item-address > small:after {
    content: " USD";
}

Listing details pages

tr[data-attribute="price"] > td:last-child:after {
    content: " USD";
}

But potentially the plugin could include it as a feature in settings, where the site owner could choose to display that phrase. The site owner would need to confirm the price being presented is in USD, the Plugin would not be validating that information.

Eg: "[x] Show currency (USD) next to list price".