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	$214.63	7.355%	$230.416	$230.42	$230.40	$230.40
Purchase #2	$13.47	13.454%	$15.2823	$15.28	$15.30	$15.30
Purchase #3	$152.32	10.693%	$168.6076	$168.61	$168.60	$168.60
Purchase #4	$20.82	6.740%	$22.2233	$22.22	$22.20	$22.20
Purchase #5	$132.90	4.590%	$139.0001	$139.00	$139.00	$139.00
Purchase #6	$93.80	11.824%	$104.8909	$104.89	$104.90	$104.90
Purchase #7	$208.50	3.356%	$215.4973	$215.50	$215.50	$215.50
7 purchase totals =	$836.44		$895.9175	$895.92	$895.90	$895.90