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	$148.29	13.256%	$167.9473	$167.95	$167.95	$167.90
Purchase #2	$177.60	11.590%	$198.1838	$198.18	$198.20	$198.20
Purchase #3	$138.88	9.310%	$151.8097	$151.81	$151.80	$151.80
Purchase #4	$62.89	8.225%	$68.0627	$68.06	$68.05	$68.10
Purchase #5	$113.38	5.435%	$119.5422	$119.54	$119.55	$119.50
Purchase #6	$221.46	4.351%	$231.0957	$231.10	$231.10	$231.10
Purchase #7	$104.39	4.853%	$109.456	$109.46	$109.45	$109.50
7 purchase totals =	$966.89		$1,046.0974	$1,046.10	$1,046.10	$1,046.10