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	$190.45	4.790%	$199.5726	$199.57	$199.55	$199.60
Purchase #2	$164.92	12.534%	$185.5911	$185.59	$185.60	$185.60
Purchase #3	$123.54	13.347%	$140.0289	$140.03	$140.05	$140.00
Purchase #4	$146.32	10.401%	$161.5387	$161.54	$161.55	$161.50
Purchase #5	$194.28	9.268%	$212.2859	$212.29	$212.30	$212.30
Purchase #6	$138.27	3.261%	$142.779	$142.78	$142.80	$142.80
Purchase #7	$55.93	10.641%	$61.8815	$61.88	$61.90	$61.90
7 purchase totals =	$1,013.71		$1,103.6777	$1,103.68	$1,103.75	$1,103.70