If your gross pay is $2000 per month and you are depositing $200 into the 401-K, the company sees this as a 10% contribution.
If they match 100% up to 5% they will contribute 5% of the gross or $100 per month.
It doesn't matermatter if your contribution is pre- or post tax,-tax and it doesn't matter to the company what your tax bracket is. Also note that all of their contributions are considered pre-tax.
Keep in mind that in the quoted example it ignored social securitySocial Security, medicareMedicare, state taxes, health insurance...