Reasonable optimized chart scaling

Question

I need to make a chart with an optimized y axis maximum value.

The current method I have of making charts simply uses the maximum value of all the graphs, then

Answer 1

A slight refinement and tested... (works for fractions of units and not just integers)

public void testNumbers() {
        double test = 0.20000;

        double multiple = 1;
        int scale = 0;
        String[] prefix = new String[]{"", "m", "u", "n"};
        while (Math.log10(test) < 0) {
            multiple = multiple * 1000;
            test = test * 1000;
            scale++;
        }

        double tick;
        double minimum = test / 10;
        double magnitude = 100000000;
        while (minimum <= magnitude){
            magnitude = magnitude / 10;
        }

        double residual = test / (magnitude * 10);
        if (residual > 5) {
            tick = 10 * magnitude;
        } else if (residual > 2) {
            tick = 5 * magnitude;
        } else if (residual > 1) {
            tick = 2 * magnitude;
        } else {
            tick = magnitude;
        }

        double curAmt = 0;

        int ticks = (int) Math.ceil(test / tick);

        for (int ix = 0; ix < ticks; ix++) {
            curAmt += tick;
            BigDecimal bigDecimal = new BigDecimal(curAmt);
            bigDecimal.setScale(2, BigDecimal.ROUND_HALF_UP);
            System.out.println(bigDecimal.stripTrailingZeros().toPlainString() + prefix[scale] + "s");
        }

        System.out.println("Value = " + test + prefix[scale] + "s");
        System.out.println("Tick = " + tick + prefix[scale] + "s");
        System.out.println("Ticks = " + ticks);
        System.out.println("Scale = " +  multiple + " : " + scale);


    }