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	$128.60	9.128%	$140.3386	$140.34	$140.35	$140.30
Purchase #2	$236.70	6.174%	$251.3139	$251.31	$251.30	$251.30
Purchase #3	$210.73	3.123%	$217.3111	$217.31	$217.30	$217.30
Purchase #4	$99.76	4.170%	$103.92	$103.92	$103.90	$103.90
Purchase #5	$87.61	13.444%	$99.3883	$99.39	$99.40	$99.40
Purchase #6	$48.61	7.790%	$52.3967	$52.40	$52.40	$52.40
Purchase #7	$144.63	4.670%	$151.3842	$151.38	$151.40	$151.40
7 purchase totals =	$956.64		$1,016.0528	$1,016.05	$1,016.05	$1,016.00