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	$106.32	4.456%	$111.0576	$111.06	$111.05	$111.10
Purchase #2	$147.63	11.447%	$164.5292	$164.53	$164.55	$164.50
Purchase #3	$55.69	10.760%	$61.6822	$61.68	$61.70	$61.70
Purchase #4	$232.39	10.420%	$256.605	$256.61	$256.60	$256.60
Purchase #5	$143.83	7.461%	$154.5612	$154.56	$154.55	$154.60
Purchase #6	$116.62	10.109%	$128.4091	$128.41	$128.40	$128.40
Purchase #7	$228.33	5.463%	$240.8037	$240.80	$240.80	$240.80
7 purchase totals =	$1,030.81		$1,117.6480	$1,117.65	$1,117.65	$1,117.70