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	$186.68	13.699%	$212.2533	$212.25	$212.25	$212.30
Purchase #2	$92.82	3.377%	$95.9545	$95.95	$95.95	$96.00
Purchase #3	$173.75	10.335%	$191.7071	$191.71	$191.70	$191.70
Purchase #4	$201.72	5.454%	$212.7218	$212.72	$212.70	$212.70
Purchase #5	$57.86	6.462%	$61.5989	$61.60	$61.60	$61.60
Purchase #6	$90.74	13.552%	$103.0371	$103.04	$103.05	$103.00
Purchase #7	$241.70	10.355%	$266.728	$266.73	$266.75	$266.70
7 purchase totals =	$1,045.27		$1,144.0007	$1,144.00	$1,144.00	$1,144.00