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	$216.98	7.598%	$233.4661	$233.47	$233.45	$233.50
Purchase #2	$214.41	9.262%	$234.2687	$234.27	$234.25	$234.30
Purchase #3	$187.57	11.482%	$209.1068	$209.11	$209.10	$209.10
Purchase #4	$246.52	9.349%	$269.5672	$269.57	$269.55	$269.60
Purchase #5	$117.60	8.426%	$127.509	$127.51	$127.50	$127.50
Purchase #6	$47.80	10.691%	$52.9103	$52.91	$52.90	$52.90
Purchase #7	$87.40	13.468%	$99.171	$99.17	$99.15	$99.20
7 purchase totals =	$1,118.28		$1,225.9991	$1,226.01	$1,225.90	$1,226.10