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	$87.28	11.305%	$97.147	$97.15	$97.15	$97.10
Purchase #2	$85.97	7.773%	$92.6524	$92.65	$92.65	$92.70
Purchase #3	$145.50	5.816%	$153.9623	$153.96	$153.95	$154.00
Purchase #4	$101.74	9.317%	$111.2191	$111.22	$111.20	$111.20
Purchase #5	$211.30	10.313%	$233.0914	$233.09	$233.10	$233.10
Purchase #6	$121.37	8.167%	$131.2823	$131.28	$131.30	$131.30
Purchase #7	$111.72	13.844%	$127.1865	$127.19	$127.20	$127.20
7 purchase totals =	$864.88		$946.5410	$946.54	$946.55	$946.60