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	$103.29	7.566%	$111.1049	$111.10	$111.10	$111.10
Purchase #2	$189.64	7.306%	$203.4951	$203.50	$203.50	$203.50
Purchase #3	$174.67	9.312%	$190.9353	$190.94	$190.95	$190.90
Purchase #4	$82.75	3.325%	$85.5014	$85.50	$85.50	$85.50
Purchase #5	$174.69	11.793%	$195.2912	$195.29	$195.30	$195.30
Purchase #6	$197.94	10.530%	$218.7831	$218.78	$218.80	$218.80
Purchase #7	$173.29	10.377%	$191.2723	$191.27	$191.25	$191.30
7 purchase totals =	$1,096.27		$1,196.3833	$1,196.38	$1,196.40	$1,196.40