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	$75.86	10.314%	$83.6842	$83.68	$83.70	$83.70
Purchase #2	$169.26	5.831%	$179.1296	$179.13	$179.15	$179.10
Purchase #3	$179.52	8.323%	$194.4614	$194.46	$194.45	$194.50
Purchase #4	$64.56	10.822%	$71.5467	$71.55	$71.55	$71.50
Purchase #5	$208.25	6.403%	$221.5842	$221.58	$221.60	$221.60
Purchase #6	$161.95	3.496%	$167.6118	$167.61	$167.60	$167.60
Purchase #7	$193.78	6.745%	$206.8505	$206.85	$206.85	$206.90
7 purchase totals =	$1,053.18		$1,124.8684	$1,124.86	$1,124.90	$1,124.90