open (FILE, "$record") or die "can't open $record: $!";
my @record = reverse <FILE>;
this is considered bad due to the fact that the file could eventually get large and fill up your memory. have a look at File::ReadBackwards
%member = ( $timestamp =>
[$current_time, $funds, $action, $current_funds]);
this is 100% wrong, because %member contains afterwards exactly one element, the ten that got into before are lost.
[$current_time, $funds, $action, $current_funds];
then, you really want to
use strict; #damn ;)
or an equivalent module. see the tutorials for why.
update: i just realized that you don't chomp;
your input lines. so, the last elem will have a line separator character at its end.
btw i hope formatting is correct ...