How can I add a 5% surcharge to all orders at checkout

Hello,

The best way to proceed, can be to add in all your payment method a Percentage of 5%, in the Generic Configuration part.
Now, this will required maybe some adjustments like hide price aside payment method in checkout (via Css), Add a block Text in your Checkout Workflow in order to inform customers of this additional cost, and create an language override to modify the "payment fee" translation (see this documentation ).

Hope this will help you to achieved your need.
Regards

Hi,

In that case, you could use an auto loaded coupon with a negative percentage.
However, this means that users wouldn't be able to enter coupons on your checkout, unless you add the multicoupon plugin we have on our marketplace.

Or, you could also do it with a tax rule as Yaya27 said: You would have to activate the "cumulative tax" setting of your tax rule(s) and create a tax rule for the 5% surcharge and configure it to apply to the tax category of the products but not the tax category of the shipping methods. That way, you would get two tax rows on the checkout, one for VAT, one for that 5% surcharge.