To do this you have to multiply the total ($17.97) by the tax percentage but as a decimal (5% = 0.05), then add the result of the multiplication to the total. Like this ($17.97)*(0.05) = 0.8985 round to either 0.89 or 0.90. Then add this to the total: $17.97 + $0.89 = $18.86 or $18.87 depending on how you round.
