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	$219.43	8.471%	$238.0179	$238.02	$238.00	$238.00
Purchase #2	$168.32	3.373%	$173.9974	$174.00	$174.00	$174.00
Purchase #3	$211.70	9.836%	$232.5228	$232.52	$232.50	$232.50
Purchase #4	$118.78	7.723%	$127.9534	$127.95	$127.95	$128.00
Purchase #5	$142.93	8.458%	$155.019	$155.02	$155.00	$155.00
Purchase #6	$248.86	10.821%	$275.7891	$275.79	$275.80	$275.80
Purchase #7	$57.76	6.627%	$61.5878	$61.59	$61.60	$61.60
7 purchase totals =	$1,167.78		$1,264.8874	$1,264.89	$1,264.85	$1,264.90