Conditional INNER JOIN

Is it possible to do a conditional INNER JOIN ?

So far I have 

SELECT * FROM ( shopping_cart_orders INNER JOIN
shopping_cart_sales_shipping_address ON
shopping_cart_orders.shipping_address_reference =
shopping_cart_sales_shipping_address.reference )

If shopping_cart_sales_shipping_address.same_as_customer has a value of
"0" I need to 

INNER JOIN shopping_cart_sales_billing_address WHERE
shopping_cart_sales_billing_address.shipping_address_reference =
shopping_cart_sales_shipping_address.reference

otherwise the shipping address is the same as the billing address.
Suggestions?

Ron