BookingCentral allows your customers to add more than one product/rental/activity to their booking. In order to allow this for online booking, the Continue Shopping feature needs to be enabled in the account.
To enable, go to Settings - Web Sales.
Select the Advanced Settings tab.
In the Cart Page section, check the 'Show Continue Shopping button on cart' page setting.
By default the button on the checkout will say, "Continue Shopping", but you can customize the text here.
During online checkout, the customer will now have the option to "Continue Shopping" before they Checkout.