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	$176.48	11.428%	$196.6481	$196.65	$196.65	$196.60
Purchase #2	$154.47	4.279%	$161.0798	$161.08	$161.10	$161.10
Purchase #3	$146.91	3.361%	$151.8476	$151.85	$151.85	$151.80
Purchase #4	$115.73	8.346%	$125.3888	$125.39	$125.40	$125.40
Purchase #5	$100.44	11.293%	$111.7827	$111.78	$111.80	$111.80
Purchase #6	$123.84	7.111%	$132.6463	$132.65	$132.65	$132.60
Purchase #7	$201.99	9.183%	$220.5387	$220.54	$220.55	$220.50
7 purchase totals =	$1,019.86		$1,099.9320	$1,099.94	$1,100.00	$1,099.80