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	$161.86	11.850%	$181.0404	$181.04	$181.05	$181.00
Purchase #2	$12.74	8.167%	$13.7805	$13.78	$13.80	$13.80
Purchase #3	$214.35	9.310%	$234.306	$234.31	$234.30	$234.30
Purchase #4	$213.86	10.509%	$236.3345	$236.33	$236.35	$236.30
Purchase #5	$40.60	4.774%	$42.5382	$42.54	$42.55	$42.50
Purchase #6	$49.78	4.605%	$52.0724	$52.07	$52.05	$52.10
Purchase #7	$243.39	5.463%	$256.6864	$256.69	$256.70	$256.70
7 purchase totals =	$936.58		$1,016.7584	$1,016.76	$1,016.80	$1,016.70