An overseas traveler visited China on March 20, and bought a batch of Chinese herbal pieces in a tax refund shop in Beijing on March 21, and obtained the general VAT invoice and the corresponding tax

An overseas traveler visited China on March 20, and bought a batch of Chinese herbal pieces in a tax refund shop in Beijing on March 21, and obtained the general VAT invoice and the corresponding tax refund application form issued by the tax refund shop on the same day. The invoice indicated that the tax rate was 10%. On April 25th, when the overseas passenger leaves the country, which tax rebate rate should be used to calculate the tax rebate for Chinese herbal pieces when handling the tax refund for the passenger?