This skill has become redundant in an era where cash registers calculate the amount of change. Hence I was taken aback (and pleasantly surprised) when the (relatively young) cashier in a supermarket recently handed me my change and counted it out to me in this way.
Perhaps the passing of this is not really a cause for regret, as the requirement for the cashier to key in the denomination of the note that they've been handed reduces the margin for "error". I can well remember my mother being very upset when she was handed change in the milk bar for a 10/- note, yet she was adamant that she had handed over a £1 note. Even today I get edgy when the cashier places the note in the drawer before taking out the change, especially if a modern till isn't in use, or isn't used to calculate the change.