Best method to round up to the nearest 0.05 in java

Question

Consider that a tax of 10% is applicable on all items except food. Also, an additional tax of of 5 % is applicable on imported items.

If the cost of a music CD is

Answer 1

This seems to be part of a famous tech interview problem The point is to understand that you have to calculate the taxes and round that amount to the upper 0.05 to calculate the rounding i used this groovy script

import java.math.*

def myRound(BigDecimal d){ 
    def scale = new BigDecimal("0.05")
    def y = d.divide(scale)
    println "y :$y"
//    def q = y.round(new MathContext(0,RoundingMode.UP))
    def q = y.setScale(0,BigDecimal.ROUND_UP)
    println "q :$q (intero)"
    def z = q.multiply(scale)
    println "z :$z"
    return z
}

def taxBy(BigDecimal d,BigDecimal t){ 
    return myRound(d.multiply(t))
}
def importTax(BigDecimal d){ 
    return taxBy(d,new BigDecimal("0.15"))
}

def importBaseTax(BigDecimal b){ 
    return taxBy(d,new BigDecimal("0.05"))
}

ip = new BigDecimal("27.99")
ipt = importTax(ip)

println "${ip}-->${ipt} = ${ip+ipt}"

I hope this to be useful!