See the comments following the fround member descriptions in the Math::BigFloat docs.

use Math::BigFloat;

my $num = Math::BigFloat->new (0.006185625);

print "Before: $num\n";
$num->fround (6, 'odd');
print "After:  $num\n";
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Prints:

Before: 0.006185625
After:  0.00618563
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