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	$221.90	10.338%	$244.84	$244.84	$244.85	$244.80
Purchase #2	$170.95	7.566%	$183.8841	$183.88	$183.90	$183.90
Purchase #3	$47.26	11.318%	$52.6089	$52.61	$52.60	$52.60
Purchase #4	$215.86	4.216%	$224.9607	$224.96	$224.95	$225.00
Purchase #5	$105.98	11.113%	$117.7576	$117.76	$117.75	$117.80
Purchase #6	$239.86	6.444%	$255.3166	$255.32	$255.30	$255.30
Purchase #7	$103.79	12.401%	$116.661	$116.66	$116.65	$116.70
7 purchase totals =	$1,105.60		$1,196.0289	$1,196.03	$1,196.00	$1,196.10