I think there is no regular option to invert the axis.
What you can try is to invert the expression by multiplying it with -1
For example like sum(value)*-1
Then you format the number to "Currency" with the format -#.##0;#.##0 so that the positive values are shown as negative values.
But this only works for the values in the chartline (for example on mouseover) and not for the axis.