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	$196.97	4.414%	$205.6643	$205.66	$205.65	$205.70
Purchase #2	$245.63	7.387%	$263.7747	$263.77	$263.75	$263.80
Purchase #3	$136.55	10.142%	$150.3989	$150.40	$150.40	$150.40
Purchase #4	$152.71	11.485%	$170.2487	$170.25	$170.25	$170.20
Purchase #5	$174.25	6.501%	$185.578	$185.58	$185.60	$185.60
Purchase #6	$138.82	4.464%	$145.0169	$145.02	$145.00	$145.00
Purchase #7	$178.28	6.831%	$190.4583	$190.46	$190.45	$190.50
7 purchase totals =	$1,223.21		$1,311.1398	$1,311.14	$1,311.10	$1,311.20