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	$238.75	3.395%	$246.8556	$246.86	$246.85	$246.90
Purchase #2	$80.27	3.328%	$82.9414	$82.94	$82.95	$82.90
Purchase #3	$63.35	11.391%	$70.5662	$70.57	$70.55	$70.60
Purchase #4	$232.73	9.382%	$254.5647	$254.56	$254.55	$254.60
Purchase #5	$124.85	5.785%	$132.0726	$132.07	$132.05	$132.10
Purchase #6	$180.89	8.675%	$196.5822	$196.58	$196.60	$196.60
Purchase #7	$141.52	6.260%	$150.3792	$150.38	$150.40	$150.40
7 purchase totals =	$1,062.36		$1,133.9619	$1,133.96	$1,133.95	$1,134.10