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	$239.58	5.453%	$252.6443	$252.64	$252.65	$252.60
Purchase #2	$200.47	13.425%	$227.3831	$227.38	$227.40	$227.40
Purchase #3	$162.31	7.438%	$174.3826	$174.38	$174.40	$174.40
Purchase #4	$228.51	3.104%	$235.603	$235.60	$235.60	$235.60
Purchase #5	$95.39	4.343%	$99.5328	$99.53	$99.55	$99.50
Purchase #6	$181.50	8.243%	$196.461	$196.46	$196.45	$196.50
Purchase #7	$94.77	7.484%	$101.8626	$101.86	$101.85	$101.90
7 purchase totals =	$1,202.53		$1,287.8694	$1,287.85	$1,287.90	$1,287.90