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	$140.74	4.846%	$147.5603	$147.56	$147.55	$147.60
Purchase #2	$146.75	3.313%	$151.6118	$151.61	$151.60	$151.60
Purchase #3	$13.28	11.725%	$14.8371	$14.84	$14.85	$14.80
Purchase #4	$85.50	13.116%	$96.7142	$96.71	$96.70	$96.70
Purchase #5	$246.52	6.358%	$262.1937	$262.19	$262.20	$262.20
Purchase #6	$128.53	3.394%	$132.8923	$132.89	$132.90	$132.90
Purchase #7	$237.58	7.459%	$255.3011	$255.30	$255.30	$255.30
7 purchase totals =	$998.90		$1,061.1105	$1,061.10	$1,061.10	$1,061.10