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	$61.87	9.222%	$67.5757	$67.58	$67.60	$67.60
Purchase #2	$237.62	3.196%	$245.2143	$245.21	$245.20	$245.20
Purchase #3	$181.49	4.579%	$189.8004	$189.80	$189.80	$189.80
Purchase #4	$150.50	5.107%	$158.186	$158.19	$158.20	$158.20
Purchase #5	$141.64	9.773%	$155.4825	$155.48	$155.50	$155.50
Purchase #6	$196.66	9.266%	$214.8825	$214.88	$214.90	$214.90
Purchase #7	$62.65	4.194%	$65.2775	$65.28	$65.30	$65.30
7 purchase totals =	$1,032.43		$1,096.4189	$1,096.42	$1,096.50	$1,096.50