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	$212.54	3.180%	$219.2988	$219.30	$219.30	$219.30
Purchase #2	$190.41	7.641%	$204.9592	$204.96	$204.95	$205.00
Purchase #3	$44.31	3.305%	$45.7744	$45.77	$45.75	$45.80
Purchase #4	$127.97	11.665%	$142.8977	$142.90	$142.90	$142.90
Purchase #5	$242.68	5.684%	$256.4739	$256.47	$256.45	$256.50
Purchase #6	$96.64	3.763%	$100.2766	$100.28	$100.30	$100.30
Purchase #7	$85.64	11.629%	$95.5991	$95.60	$95.60	$95.60
7 purchase totals =	$1,000.19		$1,065.2797	$1,065.28	$1,065.25	$1,065.40