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	$65.43	9.248%	$71.481	$71.48	$71.50	$71.50
Purchase #2	$16.31	11.209%	$18.1382	$18.14	$18.15	$18.10
Purchase #3	$112.60	13.643%	$127.962	$127.96	$127.95	$128.00
Purchase #4	$222.68	4.200%	$232.0326	$232.03	$232.05	$232.00
Purchase #5	$108.41	7.614%	$116.6643	$116.66	$116.65	$116.70
Purchase #6	$179.85	6.106%	$190.8316	$190.83	$190.85	$190.80
Purchase #7	$244.58	5.617%	$258.3181	$258.32	$258.30	$258.30
7 purchase totals =	$949.86		$1,015.4278	$1,015.42	$1,015.45	$1,015.40