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	$11.40	8.370%	$12.3542	$12.35	$12.35	$12.40
Purchase #2	$118.43	7.465%	$127.2708	$127.27	$127.25	$127.30
Purchase #3	$84.75	11.411%	$94.4208	$94.42	$94.40	$94.40
Purchase #4	$87.57	5.414%	$92.311	$92.31	$92.30	$92.30
Purchase #5	$188.45	11.461%	$210.0483	$210.05	$210.05	$210.00
Purchase #6	$132.46	7.581%	$142.5018	$142.50	$142.50	$142.50
Purchase #7	$209.31	3.510%	$216.6568	$216.66	$216.65	$216.70
7 purchase totals =	$832.37		$895.5637	$895.56	$895.50	$895.60