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	$168.28	3.422%	$174.0385	$174.04	$174.05	$174.00
Purchase #2	$175.61	8.449%	$190.4473	$190.45	$190.45	$190.40
Purchase #3	$199.62	5.830%	$211.2578	$211.26	$211.25	$211.30
Purchase #4	$118.96	3.823%	$123.5078	$123.51	$123.50	$123.50
Purchase #5	$143.94	11.126%	$159.9548	$159.95	$159.95	$160.00
Purchase #6	$132.38	4.146%	$137.8685	$137.87	$137.85	$137.90
Purchase #7	$56.53	10.150%	$62.2678	$62.27	$62.25	$62.30
7 purchase totals =	$995.32		$1,059.3425	$1,059.35	$1,059.30	$1,059.40