Mrs. Majuki and I visited a new mall in New Taipei City, and both Uniqlo and one of the restaurants had DCC (with the same terminals). At Uniqlo, the terminal was unfortunately behind the counter, and the employee tapped Mrs. Majuki's card. The cashier did hand the terminal over for the currency selection. At the restaurant, which was pay when exiting, the terminal was customer facing. Furthermore, the signature was electronically captured, so there's no confirmation of the currency selection other than the amount does appear on the signature pad. Perhaps in the case of forced DCC that you could refuse to sign: