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	$113.83	10.477%	$125.756	$125.76	$125.75	$125.80
Purchase #2	$201.45	5.238%	$212.002	$212.00	$212.00	$212.00
Purchase #3	$176.49	11.347%	$196.5163	$196.52	$196.50	$196.50
Purchase #4	$130.98	8.246%	$141.7806	$141.78	$141.80	$141.80
Purchase #5	$237.27	5.661%	$250.7019	$250.70	$250.70	$250.70
Purchase #6	$44.51	5.335%	$46.8846	$46.88	$46.90	$46.90
Purchase #7	$85.40	5.317%	$89.9407	$89.94	$89.95	$89.90
7 purchase totals =	$989.93		$1,063.5821	$1,063.58	$1,063.60	$1,063.60