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	$167.52	6.217%	$177.9347	$177.93	$177.95	$177.90
Purchase #2	$190.55	3.200%	$196.6476	$196.65	$196.65	$196.60
Purchase #3	$162.85	11.855%	$182.1559	$182.16	$182.15	$182.20
Purchase #4	$208.96	12.707%	$235.5125	$235.51	$235.50	$235.50
Purchase #5	$208.55	6.643%	$222.404	$222.40	$222.40	$222.40
Purchase #6	$241.90	9.509%	$264.9023	$264.90	$264.90	$264.90
Purchase #7	$184.56	5.439%	$194.5982	$194.60	$194.60	$194.60
7 purchase totals =	$1,364.89		$1,474.1552	$1,474.15	$1,474.15	$1,474.10