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	$195.86	8.806%	$213.1074	$213.11	$213.10	$213.10
Purchase #2	$59.42	9.574%	$65.1089	$65.11	$65.10	$65.10
Purchase #3	$159.76	12.319%	$179.4408	$179.44	$179.45	$179.40
Purchase #4	$45.68	5.560%	$48.2198	$48.22	$48.20	$48.20
Purchase #5	$183.43	7.229%	$196.6902	$196.69	$196.70	$196.70
Purchase #6	$149.63	6.631%	$159.552	$159.55	$159.55	$159.60
Purchase #7	$175.46	5.731%	$185.5156	$185.52	$185.50	$185.50
7 purchase totals =	$969.24		$1,047.6347	$1,047.64	$1,047.60	$1,047.60