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	$218.27	10.674%	$241.5681	$241.57	$241.55	$241.60
Purchase #2	$217.86	6.638%	$232.3215	$232.32	$232.30	$232.30
Purchase #3	$205.64	8.404%	$222.922	$222.92	$222.90	$222.90
Purchase #4	$12.74	8.678%	$13.8456	$13.85	$13.85	$13.80
Purchase #5	$160.55	13.294%	$181.8935	$181.89	$181.90	$181.90
Purchase #6	$157.81	9.189%	$172.3112	$172.31	$172.30	$172.30
Purchase #7	$38.71	11.517%	$43.1682	$43.17	$43.15	$43.20
7 purchase totals =	$1,011.58		$1,108.0301	$1,108.03	$1,107.95	$1,108.00