If you want to round up to one less than the magnitude like this:

$ perl -Mstrict -MPOSIX=ceil,floor -wE'
for my $peak (0.1,0.9,2.1,9.9,11,22.22,35,111,265,999,1020,120010) {
    my $base = 10**( floor(log($peak)/log(10)) - 1 );
    my $h = ceil($peak/$base) * $base;
    $h += $base if $h == $peak;  # avoid peak = max
    printf "%s\t%s\n", $peak, $h;
}
'
0.1    0.11
0.9    0.91
2.1    2.2
9.9    10
11    12
22.22    23
35    36
111    120
265    270
999    1000
1020    1100
120010    130000
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