I recently went through the rig moral of employing staff - and one things for sure - payroll software is expensive when you consider the costs over an entire year.
I found the cheapest way of managing less than 5 employees to be on a plain old simple Excel Spreadsheet.
Using Online resource provided by the IRD - you can calculate exactly how much tax someone should be paying and just update the spreadsheet each week.
You can calculate holiday pay as a simple percentage of their Gross Pay (8%).
Would love to hear some of the home brew methods people use for managing payrolls.