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	$219.36	11.208%	$243.9459	$243.95	$243.95	$243.90
Purchase #2	$203.52	13.584%	$231.1662	$231.17	$231.15	$231.20
Purchase #3	$63.33	7.220%	$67.9024	$67.90	$67.90	$67.90
Purchase #4	$141.42	3.664%	$146.6016	$146.60	$146.60	$146.60
Purchase #5	$177.70	6.777%	$189.7427	$189.74	$189.75	$189.70
Purchase #6	$93.97	5.768%	$99.3902	$99.39	$99.40	$99.40
Purchase #7	$145.72	13.753%	$165.7609	$165.76	$165.75	$165.80
7 purchase totals =	$1,045.02		$1,144.5099	$1,144.51	$1,144.50	$1,144.50