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	$194.91	5.844%	$206.3005	$206.30	$206.30	$206.30
Purchase #2	$103.27	7.822%	$111.3478	$111.35	$111.35	$111.30
Purchase #3	$204.85	4.124%	$213.298	$213.30	$213.30	$213.30
Purchase #4	$67.88	10.472%	$74.9884	$74.99	$75.00	$75.00
Purchase #5	$70.50	11.751%	$78.7845	$78.78	$78.80	$78.80
Purchase #6	$232.60	6.448%	$247.598	$247.60	$247.60	$247.60
Purchase #7	$76.88	13.162%	$86.9989	$87.00	$87.00	$87.00
7 purchase totals =	$950.89		$1,019.3161	$1,019.32	$1,019.35	$1,019.30