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	$245.50	7.255%	$263.311	$263.31	$263.30	$263.30
Purchase #2	$39.44	5.775%	$41.7177	$41.72	$41.70	$41.70
Purchase #3	$189.65	3.582%	$196.4433	$196.44	$196.45	$196.40
Purchase #4	$89.69	6.654%	$95.658	$95.66	$95.65	$95.70
Purchase #5	$50.67	7.321%	$54.3796	$54.38	$54.40	$54.40
Purchase #6	$233.92	3.739%	$242.6663	$242.67	$242.65	$242.70
Purchase #7	$249.27	13.418%	$282.717	$282.72	$282.70	$282.70
7 purchase totals =	$1,098.14		$1,176.8929	$1,176.90	$1,176.85	$1,176.90