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	$188.43	13.600%	$214.0565	$214.06	$214.05	$214.10
Purchase #2	$57.89	4.644%	$60.5784	$60.58	$60.60	$60.60
Purchase #3	$162.54	5.630%	$171.691	$171.69	$171.70	$171.70
Purchase #4	$117.64	12.523%	$132.3721	$132.37	$132.35	$132.40
Purchase #5	$85.82	11.274%	$95.4953	$95.50	$95.50	$95.50
Purchase #6	$134.85	5.801%	$142.6726	$142.67	$142.65	$142.70
Purchase #7	$211.39	7.823%	$227.927	$227.93	$227.95	$227.90
7 purchase totals =	$958.56		$1,044.7929	$1,044.80	$1,044.80	$1,044.90