The National Health Insurance Levy — 2.5% charged on the value of most supplies, funding the NHIS.
It is one of three levies, alongside the GETFund levy and the COVID-19 Health Recovery Levy, charged on the value of a supply before VAT is applied. VAT is then charged on the total including them.
That compounding is why the effective tax on a purchase in Ghana is considerably higher than the headline VAT rate.
This levy is also why NHIS membership costs so little at the point of registration — you have been paying for it all year, at every till.