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	$57.92	7.643%	$62.3468	$62.35	$62.35	$62.30
Purchase #2	$19.61	8.785%	$21.3327	$21.33	$21.35	$21.30
Purchase #3	$149.76	5.462%	$157.9399	$157.94	$157.95	$157.90
Purchase #4	$92.89	13.451%	$105.3846	$105.38	$105.40	$105.40
Purchase #5	$165.80	8.758%	$180.3208	$180.32	$180.30	$180.30
Purchase #6	$170.74	12.163%	$191.5071	$191.51	$191.50	$191.50
Purchase #7	$218.82	4.323%	$228.2796	$228.28	$228.30	$228.30
7 purchase totals =	$875.54		$947.1115	$947.11	$947.15	$947.00