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	$167.47	10.603%	$185.2268	$185.23	$185.25	$185.20
Purchase #2	$113.33	10.291%	$124.9928	$124.99	$125.00	$125.00
Purchase #3	$130.68	5.205%	$137.4819	$137.48	$137.50	$137.50
Purchase #4	$232.33	3.845%	$241.2631	$241.26	$241.25	$241.30
Purchase #5	$11.72	13.743%	$13.3307	$13.33	$13.35	$13.30
Purchase #6	$245.48	8.706%	$266.8515	$266.85	$266.85	$266.90
Purchase #7	$114.42	11.462%	$127.5348	$127.53	$127.55	$127.50
7 purchase totals =	$1,015.43		$1,096.6816	$1,096.67	$1,096.75	$1,096.70