if ($total eq "3") {
 $revenue = 30;
 } elsif ($total eq "6") {
 $revenue = 48;
 } elsif ($total eq "10") {
 $revenue = 50;
 }
[download]

Is it the case that what you're really after is:

 if ($total eq "3") {
 $revenue += 30;
 }
 if ($total eq "6") {
 $revenue += 48;
 }
 if ($total eq "10") {
 $revenue += 50;
 }
[download]

Hmmm .... on some reflection, replacing "elsif" with "if" (as I have done), doesn't really achieve anything.
And replacing "+" with "+=" does, of course, change things only if the code is run more than once.
I now think that maybe I don't understand the problem at all ....

Cheers,
Rob