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	$194.79	3.446%	$201.5025	$201.50	$201.50	$201.50
Purchase #2	$165.89	13.601%	$188.4527	$188.45	$188.45	$188.50
Purchase #3	$142.46	8.291%	$154.2714	$154.27	$154.25	$154.30
Purchase #4	$50.84	5.132%	$53.4491	$53.45	$53.45	$53.40
Purchase #5	$201.61	10.336%	$222.4484	$222.45	$222.45	$222.40
Purchase #6	$228.97	10.114%	$252.128	$252.13	$252.15	$252.10
Purchase #7	$71.46	9.874%	$78.516	$78.52	$78.50	$78.50
7 purchase totals =	$1,056.02		$1,150.7681	$1,150.77	$1,150.75	$1,150.70