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	$88.47	7.588%	$95.1831	$95.18	$95.20	$95.20
Purchase #2	$199.76	3.358%	$206.4679	$206.47	$206.45	$206.50
Purchase #3	$214.65	8.669%	$233.258	$233.26	$233.25	$233.30
Purchase #4	$135.97	12.220%	$152.5855	$152.59	$152.60	$152.60
Purchase #5	$193.48	3.537%	$200.3234	$200.32	$200.30	$200.30
Purchase #6	$199.60	4.228%	$208.0391	$208.04	$208.05	$208.00
Purchase #7	$122.72	3.198%	$126.6446	$126.64	$126.65	$126.60
7 purchase totals =	$1,154.65		$1,222.5016	$1,222.50	$1,222.50	$1,222.50