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	$90.94	7.842%	$98.0715	$98.07	$98.05	$98.10
Purchase #2	$59.44	8.712%	$64.6184	$64.62	$64.60	$64.60
Purchase #3	$86.94	5.795%	$91.9782	$91.98	$92.00	$92.00
Purchase #4	$49.71	6.504%	$52.9431	$52.94	$52.95	$52.90
Purchase #5	$214.32	10.503%	$236.83	$236.83	$236.85	$236.80
Purchase #6	$226.33	13.477%	$256.8325	$256.83	$256.85	$256.80
Purchase #7	$86.30	9.136%	$94.1844	$94.18	$94.20	$94.20
7 purchase totals =	$813.98		$895.4581	$895.45	$895.50	$895.40