Indian restaurants are usually 5% GST without input credit. 18% applies inside hotels with room tariff above ₹7,500. Whatever you set here is frozen onto each order the moment it opens — changing it never re-prices a bill that is already running.

Tax invoices run on their own consecutive series, separate from counter bill numbers. Place of supply is your state and never the customer's: restaurant service is taxed where it is served, so the invoice is always CGST + SGST even for an out-of-state company. Note that a customer normally cannot claim input credit on food and beverage — they still need the invoice for their own records.