Ruby Big Decimal Rounding with fixed number

Question

I want to round a BigDecimal in ruby. I know I can use the round function but

the round function gives

(3.2).round(2) =>  3.2

I want

(3.2).round(2) =>  3.20
(3.20).round(2) =>  3.20
(3).round(2) =>  3.00
(3.578).round(2) =>  3.58

I always want to have 2 decimal places, 3.20 not 3.2

any idea how to get this done ?

Solution

Unlike, for example, Java's BigDecimal, Ruby's BigDecimal does not have a per-instance precision. The difference between 3.2 and 3.20 in a Ruby BigDecimal is just formatting.