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	$167.96	3.650%	$174.0905	$174.09	$174.10	$174.10
Purchase #2	$119.61	4.149%	$124.5726	$124.57	$124.55	$124.60
Purchase #3	$54.89	13.775%	$62.4511	$62.45	$62.45	$62.50
Purchase #4	$146.64	6.799%	$156.6101	$156.61	$156.60	$156.60
Purchase #5	$227.47	4.779%	$238.3408	$238.34	$238.35	$238.30
Purchase #6	$161.67	4.856%	$169.5207	$169.52	$169.50	$169.50
Purchase #7	$194.65	6.481%	$207.2653	$207.27	$207.25	$207.30
7 purchase totals =	$1,072.89		$1,132.8511	$1,132.85	$1,132.80	$1,132.90