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	$187.59	9.479%	$205.3717	$205.37	$205.35	$205.40
Purchase #2	$65.72	10.294%	$72.4852	$72.49	$72.50	$72.50
Purchase #3	$27.64	10.743%	$30.6094	$30.61	$30.60	$30.60
Purchase #4	$237.56	12.151%	$266.4259	$266.43	$266.45	$266.40
Purchase #5	$100.81	3.195%	$104.0309	$104.03	$104.05	$104.00
Purchase #6	$209.41	8.713%	$227.6559	$227.66	$227.65	$227.70
Purchase #7	$122.28	4.471%	$127.7471	$127.75	$127.75	$127.70
7 purchase totals =	$951.01		$1,034.3261	$1,034.34	$1,034.35	$1,034.30