A continually decaying value would be complex to manage, but perhaps you could achieve a similar impact following a version of the approach used in Brazil to ta

A continually decaying value would be complex to manage, but perhaps you could achieve a similar impact following a version of the approach used in Brazil to target runaway inflation. (please jump in if you know the details better than I recall) Prices and salaries were struck in a notional currency the Plano Real, but in daily life people used the Cruzeiro Real, and a daily price was struck for the conversion from Cruzeiro real to a Plano Real. Fed bank accounts balances could be in Cruzeiro Dollars, with a weekly conversion rate published to Plano Dollars