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	$91.48	11.435%	$101.9407	$101.94	$101.95	$101.90
Purchase #2	$178.49	12.362%	$200.5549	$200.55	$200.55	$200.60
Purchase #3	$180.55	8.286%	$195.5104	$195.51	$195.50	$195.50
Purchase #4	$19.33	11.752%	$21.6017	$21.60	$21.60	$21.60
Purchase #5	$150.92	3.133%	$155.6483	$155.65	$155.65	$155.60
Purchase #6	$244.58	11.465%	$272.6211	$272.62	$272.60	$272.60
Purchase #7	$100.25	11.426%	$111.7046	$111.70	$111.70	$111.70
7 purchase totals =	$965.60		$1,059.5817	$1,059.57	$1,059.55	$1,059.50