Medicare Levy Surcharge - 1%

Hi, I have the exact same question as this post that had no replies.

Medicare Levy Surcharge additional 1% withholding | MYOB Community

So copying and pasting the original message from DH30

Is there a solution for adding a percentage for the additional Medical Levy Surcharge my employee wants me to withhold each week?  My employee has requested:

Claim tax-free threshold   - Yes

Additional withholding amount    -  $0

Medicare levy variation     - 1% Medicare levy surcharge

At the moment I can only enter a $ value and this would work if my employee had the same wage amount week in week out.  I thought I could set up another Tax Payroll Category just for the additional 1% but Accountright doesn't allow me to add another category, only can edit existing standard category.  

There must be a better way than me having to calculate an additional 1% and manually add it to the amount withheld each pay.

Can anyone help?

On another post, a MYOB staff member recommended setting this up as a deduction, but there are no STP reporting category options to do that. 

As the employee's income varies from week to week, I can't simply set and forget the "extra tax $ - per pay" category. 

Do I really have to manually calculate the additional tax every week?

Note, this is not the standard medicare levy, covered by normal PAYG tax tables, it's an ADDITIONAL surcharge for not having private health insurance.