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	$216.86	11.628%	$242.0765	$242.08	$242.10	$242.10
Purchase #2	$200.56	12.235%	$225.0985	$225.10	$225.10	$225.10
Purchase #3	$181.48	8.634%	$197.149	$197.15	$197.15	$197.10
Purchase #4	$189.87	7.781%	$204.6438	$204.64	$204.65	$204.60
Purchase #5	$63.31	3.413%	$65.4708	$65.47	$65.45	$65.50
Purchase #6	$93.83	7.127%	$100.5173	$100.52	$100.50	$100.50
Purchase #7	$64.27	7.188%	$68.8897	$68.89	$68.90	$68.90
7 purchase totals =	$1,010.18		$1,103.8456	$1,103.85	$1,103.85	$1,103.80