The best practice is if you're forced into DCC is to deface the receipt by crossing out the DCC language and writing "local option not offered" before signing. Take the issue up with the card issuer by disputing the transaction.

If there is no language barrier and the cashier/merchant are receptive, try working with them to see if there is an opt-out available. Some merchants have instructed their staff to bill in home currency because they're getting a cut of the profits on the ripoff exchange rate. Many times there's an option they're bypassing or selecting for you. Other times there are hidden or post facto opt-out options like pressing cancel or going into the POS terminal menu to select the transaction currency.

Fortunately Chase, as JEFFJAGUAR pointed out, is well aware of this issue.