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	$95.35	10.192%	$105.0681	$105.07	$105.05	$105.10
Purchase #2	$132.42	7.509%	$142.3634	$142.36	$142.35	$142.40
Purchase #3	$229.60	5.118%	$241.3509	$241.35	$241.35	$241.40
Purchase #4	$116.39	7.790%	$125.4568	$125.46	$125.45	$125.50
Purchase #5	$128.93	10.615%	$142.6159	$142.62	$142.60	$142.60
Purchase #6	$65.76	5.430%	$69.3308	$69.33	$69.35	$69.30
Purchase #7	$222.72	8.581%	$241.8316	$241.83	$241.85	$241.80
7 purchase totals =	$991.17		$1,068.0175	$1,068.02	$1,068.00	$1,068.10