I have a number of custom styles, all numeric, but some have currency symbols
and some have characters after the numeric part.

I need to be able to select a range of cells which contain a mixture of
these custom number formats, and increase/decrease the number of decimal
places while retaining the old format.

The native increase/decrease decimals command applies the number format of
the first cell in the range to the entire range, so it is not suitable.

As an example, I would like an "increase decimal" to change:

£1.23
$6.97
4.557m

into

£1.233
$6.971
4.5572m

I would appreciate any help with this, Thanks.