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	$102.91	13.540%	$116.844	$116.84	$116.85	$116.80
Purchase #2	$204.90	8.402%	$222.1157	$222.12	$222.10	$222.10
Purchase #3	$130.72	11.752%	$146.0822	$146.08	$146.10	$146.10
Purchase #4	$11.31	12.222%	$12.6923	$12.69	$12.70	$12.70
Purchase #5	$196.25	5.368%	$206.7847	$206.78	$206.80	$206.80
Purchase #6	$179.64	4.249%	$187.2729	$187.27	$187.25	$187.30
Purchase #7	$118.39	10.680%	$131.0341	$131.03	$131.05	$131.00
7 purchase totals =	$944.12		$1,022.8259	$1,022.81	$1,022.85	$1,022.80