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	$205.85	11.485%	$229.4919	$229.49	$229.50	$229.50
Purchase #2	$188.61	12.836%	$212.82	$212.82	$212.80	$212.80
Purchase #3	$150.63	7.460%	$161.867	$161.87	$161.85	$161.90
Purchase #4	$200.43	5.354%	$211.161	$211.16	$211.15	$211.20
Purchase #5	$87.30	5.365%	$91.9836	$91.98	$92.00	$92.00
Purchase #6	$158.75	5.864%	$168.0591	$168.06	$168.05	$168.10
Purchase #7	$49.86	13.299%	$56.4909	$56.49	$56.50	$56.50
7 purchase totals =	$1,041.43		$1,131.8735	$1,131.87	$1,131.85	$1,132.00