How to manage USA visitors (I have a UK eCommerce site)

I have an eCommerce site (Amazon affiliated) that is UK based but now is ranking very high up on google.com so I get alot of traffic from USA and other big countries that use google.com.

My question is:
Because the prices are in £ (Great Britain Currency), USA visitors are leaving my site almost instantly. Is there a way around this without affecting any of my SEO rankings?

Thanks