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	$200.78	6.566%	$213.9632	$213.96	$213.95	$214.00
Purchase #2	$142.93	10.610%	$158.0949	$158.09	$158.10	$158.10
Purchase #3	$139.81	10.572%	$154.5907	$154.59	$154.60	$154.60
Purchase #4	$148.78	4.647%	$155.6938	$155.69	$155.70	$155.70
Purchase #5	$155.33	12.634%	$174.9544	$174.95	$174.95	$175.00
Purchase #6	$113.53	9.745%	$124.5935	$124.59	$124.60	$124.60
Purchase #7	$139.53	7.864%	$150.5026	$150.50	$150.50	$150.50
7 purchase totals =	$1,040.69		$1,132.3931	$1,132.37	$1,132.40	$1,132.50