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	$221.98	4.307%	$231.5407	$231.54	$231.55	$231.50
Purchase #2	$10.52	6.439%	$11.1974	$11.20	$11.20	$11.20
Purchase #3	$213.40	4.867%	$223.7862	$223.79	$223.80	$223.80
Purchase #4	$82.81	3.170%	$85.4351	$85.44	$85.45	$85.40
Purchase #5	$216.28	13.577%	$245.6443	$245.64	$245.65	$245.60
Purchase #6	$123.31	3.369%	$127.4643	$127.46	$127.45	$127.50
Purchase #7	$82.77	8.334%	$89.6681	$89.67	$89.65	$89.70
7 purchase totals =	$951.07		$1,014.7361	$1,014.74	$1,014.75	$1,014.70