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	$103.85	7.175%	$111.3012	$111.30	$111.30	$111.30
Purchase #2	$176.41	7.335%	$189.3497	$189.35	$189.35	$189.30
Purchase #3	$31.93	6.471%	$33.9962	$34.00	$34.00	$34.00
Purchase #4	$99.56	13.325%	$112.8264	$112.83	$112.85	$112.80
Purchase #5	$92.83	12.622%	$104.547	$104.55	$104.55	$104.50
Purchase #6	$155.55	9.573%	$170.4408	$170.44	$170.45	$170.40
Purchase #7	$200.32	9.342%	$219.0339	$219.03	$219.05	$219.00
7 purchase totals =	$860.45		$941.4952	$941.50	$941.55	$941.30