Calculations: tax, tip and fee pass-through

8.1 Sales tax

Computed on the subtotal only.

{ "amount": 100, "sales_tax_type": "percentage", "sales_tax_value": 15 }
-> subtotal 100, sales_tax_amount 15, total 115

fixed adds an amount instead of a percentage. A percentage cannot exceed 100.

8.2 Tip

tip_enabled: true forces a choice between two modes; omitting both returns 422 ("Seleccione un tipo de propina o permita la seleccion del cliente en el checkout.").

Fixed tip - set by the merchant, reflected in the total at creation:

{ "amount": 100, "tip_enabled": true, "tip_type": "percentage", "tip_value": 10 }
-> total 110

Customer-selected - the total at creation does not include a tip; the customer adds it at checkout:

{
  "amount": 100, "tip_enabled": true,
  "tip_customer_selectable": true,
  "tip_preset_percentages": [10, 15, 20],
  "tip_allow_custom": true,
  "tip_min_amount": 0, "tip_max_amount": 50
}
-> total 100 at creation; the customer decides when paying

tip_max_amount cannot exceed amount - doing so returns 422.

8.3 Passing costs to the customer (service_fee_enabled)

When enabled, ROKI's commission, the 3-D Secure charge and the tax on that commission are passed on to the customer. ROKI recomputes the total by reverse calculation so the merchant nets the requested amount.

{ "amount": 100, "service_fee_enabled": true }
-> subtotal 100, service_fee_amount 5.52, total 105.52

Never replicate this calculation on the integrator side. The rates, the fixed charge and the threshold are per-merchant configuration and they change. Read service_fee_amount and total from the response - that is the only correct source. The fee is computed on the full base (amount plus tax plus fixed tip).

The field name is exactly service_fee_enabled. The variants service_fee, service_fee_type/service_fee_value and pass_fees_to_customer are silently ignored: the API returns 201 and the payment is created without fee pass-through. See 12.1.

8.4 Reusable links (reusable)

By default a link is consumed once paid: afterwards it shows "Enlace no disponible". With reusable: true the link accepts more than one charge - useful for fixed links shared on social media.