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	$185.95	4.612%	$194.526	$194.53	$194.55	$194.50
Purchase #2	$183.35	4.456%	$191.5201	$191.52	$191.50	$191.50
Purchase #3	$72.51	4.166%	$75.5308	$75.53	$75.55	$75.50
Purchase #4	$40.78	12.164%	$45.7405	$45.74	$45.75	$45.70
Purchase #5	$171.33	8.692%	$186.222	$186.22	$186.20	$186.20
Purchase #6	$123.27	9.189%	$134.5973	$134.60	$134.60	$134.60
Purchase #7	$184.97	8.129%	$200.0062	$200.01	$200.00	$200.00
7 purchase totals =	$962.16		$1,028.1429	$1,028.15	$1,028.15	$1,028.00