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	$246.95	7.514%	$265.5058	$265.51	$265.50	$265.50
Purchase #2	$22.45	13.477%	$25.4756	$25.48	$25.50	$25.50
Purchase #3	$66.43	7.486%	$71.4029	$71.40	$71.40	$71.40
Purchase #4	$184.77	13.281%	$209.3093	$209.31	$209.30	$209.30
Purchase #5	$131.69	3.823%	$136.7245	$136.72	$136.70	$136.70
Purchase #6	$38.83	8.511%	$42.1348	$42.13	$42.15	$42.10
Purchase #7	$47.84	8.663%	$51.9844	$51.98	$52.00	$52.00
7 purchase totals =	$738.96		$802.5373	$802.53	$802.55	$802.50