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	$177.91	10.198%	$196.0533	$196.05	$196.05	$196.10
Purchase #2	$92.71	13.832%	$105.5336	$105.53	$105.55	$105.50
Purchase #3	$115.77	7.378%	$124.3115	$124.31	$124.30	$124.30
Purchase #4	$139.54	9.240%	$152.4335	$152.43	$152.45	$152.40
Purchase #5	$139.37	13.117%	$157.6512	$157.65	$157.65	$157.70
Purchase #6	$202.26	11.395%	$225.3075	$225.31	$225.30	$225.30
Purchase #7	$57.41	6.597%	$61.1973	$61.20	$61.20	$61.20
7 purchase totals =	$924.97		$1,022.4879	$1,022.48	$1,022.50	$1,022.50