Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$176.47	7.468%	$189.6488	$189.65	$189.65	$189.60
Purchase #2	$12.84	6.102%	$13.6235	$13.62	$13.60	$13.60
Purchase #3	$76.76	7.625%	$82.613	$82.61	$82.60	$82.60
Purchase #4	$180.60	6.131%	$191.6726	$191.67	$191.65	$191.70
Purchase #5	$142.77	13.482%	$162.0183	$162.02	$162.00	$162.00
Purchase #6	$205.96	13.642%	$234.0571	$234.06	$234.05	$234.10
Purchase #7	$240.64	13.678%	$273.5547	$273.55	$273.55	$273.60
7 purchase totals =	$1,036.04		$1,147.1880	$1,147.18	$1,147.10	$1,147.20