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	$196.67	4.233%	$204.995	$205.00	$205.00	$205.00
Purchase #2	$19.61	7.858%	$21.151	$21.15	$21.15	$21.20
Purchase #3	$120.49	8.327%	$130.5232	$130.52	$130.50	$130.50
Purchase #4	$112.46	4.699%	$117.7445	$117.74	$117.75	$117.70
Purchase #5	$149.54	10.593%	$165.3808	$165.38	$165.40	$165.40
Purchase #6	$189.29	11.341%	$210.7574	$210.76	$210.75	$210.80
Purchase #7	$152.84	8.236%	$165.4279	$165.43	$165.45	$165.40
7 purchase totals =	$940.90		$1,015.9798	$1,015.98	$1,016.00	$1,016.00