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	$87.52	9.406%	$95.7521	$95.75	$95.75	$95.80
Purchase #2	$240.91	10.583%	$266.4055	$266.41	$266.40	$266.40
Purchase #3	$188.30	4.413%	$196.6097	$196.61	$196.60	$196.60
Purchase #4	$113.25	6.654%	$120.7857	$120.79	$120.80	$120.80
Purchase #5	$245.89	5.353%	$259.0525	$259.05	$259.05	$259.10
Purchase #6	$140.54	9.812%	$154.3298	$154.33	$154.35	$154.30
Purchase #7	$192.27	12.167%	$215.6635	$215.66	$215.65	$215.70
7 purchase totals =	$1,208.68		$1,308.5988	$1,308.60	$1,308.60	$1,308.70