AxisCalculator

TimeAxisCalculator.cs

public static class TimeAxisCalculator
{
    private static readonly TimeSpan[] CandidateValues =
    {
        TimeSpan.FromMinutes(1),
        TimeSpan.FromMinutes(2),
        TimeSpan.FromMinutes(5),
        TimeSpan.FromMinutes(10),
        TimeSpan.FromMinutes(15),
        TimeSpan.FromMinutes(30),
        TimeSpan.FromHours(1),
        TimeSpan.FromHours(2),
        TimeSpan.FromHours(3),
        TimeSpan.FromHours(4),
        TimeSpan.FromHours(6),
        TimeSpan.FromHours(12),
        TimeSpan.FromDays(1)
    };

    public static TimeSpan Calc(TimeSpan range)
    {
        var value = range / 5;
        foreach (var candidateValue in CandidateValues)
        {
            if (value <= candidateValue)
            {
                return candidateValue;
            }
        }

        return CandidateValues[^1];
    }
}

// 00:00:01 -> 00:00:01
// 00:00:05 -> 00:00:01
// 00:00:06 -> 00:00:02
// 00:00:09 -> 00:00:02
// 00:00:10 -> 00:00:02
// 00:00:11 -> 00:00:05
// 00:00:25 -> 00:00:05
// 00:00:26 -> 00:00:10
// 00:00:50 -> 00:00:10
// 00:00:51 -> 00:00:15
// 00:01:15 -> 00:00:15
// 00:01:16 -> 00:00:30
// 00:02:30 -> 00:00:30
// 00:02:31 -> 00:01:00
// 00:05:00 -> 00:01:00
// 00:05:01 -> 00:02:00
// 00:10:00 -> 00:02:00
// 00:10:01 -> 00:03:00
// 00:15:00 -> 00:03:00
// 00:15:01 -> 00:04:00
// 00:20:00 -> 00:04:00
// 00:20:01 -> 00:06:00
// 01:06:00 -> 00:06:00
// 01:06:01 -> 00:12:00
// 02:12:00 -> 00:12:00
// 02:12:01 -> 01:00:00
// 05:00:00 -> 01:00:00

ValueAxisCalculator.cs

public static class ValueAxisCalculator
{
    public static double Calc(double value)
    {
        var baseValue = 30;
        var log = 0;
        while (value >= baseValue)
        {
            baseValue *= 10;
            log++;
        }

        var pow = (int)Math.Pow(10, log);

        if (value < 6 * pow)
        {
            return pow;
        }
        if (value < 12 * pow)
        {
            return 2 * pow;
        }
        if (value < 15 * pow)
        {
            return 2.5 * pow;
        }

        return 5 * pow;
    }
}

// 0.00 -> 1.00
// 1.00 -> 1.00
// 3.00 -> 1.00
// 5.90 -> 1.00
// 6.00 -> 2.00
// 11.90 -> 2.00
// 12.00 -> 2.50
// 14.90 -> 2.50
// 15.00 -> 5.00
// 29.90 -> 5.00
// 30.00 -> 10.00
// 59.90 -> 10.00
// 60.00 -> 20.00
// 119.90 -> 20.00
// 120.00 -> 25.00
// 149.90 -> 25.00
// 150.00 -> 50.00
// 299.90 -> 50.00
// 300.00 -> 100.00
// 599.90 -> 100.00
// 600.00 -> 200.00
// 1199.90 -> 200.00
// 1200.00 -> 250.00
// 1499.90 -> 250.00
// 1500.00 -> 500.00
// 2999.90 -> 500.00
// 3000.00 -> 1000.00
// 5999.90 -> 1000.00
// 6000.00 -> 2000.00
// 11999.90 -> 2000.00
// 12000.00 -> 2500.00
// 29999.90 -> 5000.00