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	$223.34	3.236%	$230.5673	$230.57	$230.55	$230.60
Purchase #2	$139.34	3.743%	$144.5555	$144.56	$144.55	$144.60
Purchase #3	$239.69	4.550%	$250.5959	$250.60	$250.60	$250.60
Purchase #4	$40.36	13.298%	$45.7271	$45.73	$45.75	$45.70
Purchase #5	$60.58	8.697%	$65.8486	$65.85	$65.85	$65.80
Purchase #6	$232.87	12.779%	$262.6285	$262.63	$262.65	$262.60
Purchase #7	$31.63	11.747%	$35.3456	$35.35	$35.35	$35.30
7 purchase totals =	$967.81		$1,035.2685	$1,035.29	$1,035.30	$1,035.20