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	$177.25	10.565%	$195.9765	$195.98	$196.00	$196.00
Purchase #2	$230.88	12.782%	$260.3911	$260.39	$260.40	$260.40
Purchase #3	$144.65	8.733%	$157.2823	$157.28	$157.30	$157.30
Purchase #4	$35.92	4.438%	$37.5141	$37.51	$37.50	$37.50
Purchase #5	$190.97	10.108%	$210.2732	$210.27	$210.25	$210.30
Purchase #6	$78.57	11.370%	$87.5034	$87.50	$87.50	$87.50
Purchase #7	$118.40	4.308%	$123.5007	$123.50	$123.50	$123.50
7 purchase totals =	$976.64		$1,072.4413	$1,072.43	$1,072.45	$1,072.50