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	$184.28	6.360%	$196.0002	$196.00	$196.00	$196.00
Purchase #2	$88.92	13.795%	$101.1865	$101.19	$101.20	$101.20
Purchase #3	$97.69	13.707%	$111.0804	$111.08	$111.10	$111.10
Purchase #4	$205.25	9.865%	$225.4979	$225.50	$225.50	$225.50
Purchase #5	$250.38	8.773%	$272.3458	$272.35	$272.35	$272.30
Purchase #6	$242.37	5.863%	$256.5802	$256.58	$256.60	$256.60
Purchase #7	$50.51	9.662%	$55.3903	$55.39	$55.40	$55.40
7 purchase totals =	$1,119.40		$1,218.0813	$1,218.09	$1,218.15	$1,218.10