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	$158.32	13.652%	$179.9338	$179.93	$179.95	$179.90
Purchase #2	$105.37	6.232%	$111.9367	$111.94	$111.95	$111.90
Purchase #3	$48.62	6.342%	$51.7035	$51.70	$51.70	$51.70
Purchase #4	$179.52	3.274%	$185.3975	$185.40	$185.40	$185.40
Purchase #5	$95.88	13.534%	$108.8564	$108.86	$108.85	$108.90
Purchase #6	$209.31	5.557%	$220.9414	$220.94	$220.95	$220.90
Purchase #7	$155.64	7.190%	$166.8305	$166.83	$166.85	$166.80
7 purchase totals =	$952.66		$1,025.5998	$1,025.60	$1,025.65	$1,025.50