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	$185.36	3.579%	$191.994	$191.99	$192.00	$192.00
Purchase #2	$49.89	5.170%	$52.4693	$52.47	$52.45	$52.50
Purchase #3	$168.52	9.106%	$183.8654	$183.87	$183.85	$183.90
Purchase #4	$181.91	4.724%	$190.5034	$190.50	$190.50	$190.50
Purchase #5	$107.58	4.488%	$112.4082	$112.41	$112.40	$112.40
Purchase #6	$242.69	13.729%	$276.0089	$276.01	$276.00	$276.00
Purchase #7	$94.34	10.667%	$104.4032	$104.40	$104.40	$104.40
7 purchase totals =	$1,030.29		$1,111.6524	$1,111.65	$1,111.60	$1,111.70