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	$219.79	4.421%	$229.5069	$229.51	$229.50	$229.50
Purchase #2	$187.60	6.333%	$199.4807	$199.48	$199.50	$199.50
Purchase #3	$106.52	9.144%	$116.2602	$116.26	$116.25	$116.30
Purchase #4	$16.56	7.448%	$17.7934	$17.79	$17.80	$17.80
Purchase #5	$205.73	8.306%	$222.8179	$222.82	$222.80	$222.80
Purchase #6	$20.87	6.690%	$22.2662	$22.27	$22.25	$22.30
Purchase #7	$196.76	4.558%	$205.7283	$205.73	$205.75	$205.70
7 purchase totals =	$953.83		$1,013.8536	$1,013.86	$1,013.85	$1,013.90