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	$147.52	7.615%	$158.7536	$158.75	$158.75	$158.80
Purchase #2	$85.39	6.536%	$90.9711	$90.97	$90.95	$91.00
Purchase #3	$185.48	6.413%	$197.3748	$197.37	$197.35	$197.40
Purchase #4	$246.96	7.819%	$266.2698	$266.27	$266.25	$266.30
Purchase #5	$107.45	8.811%	$116.9174	$116.92	$116.90	$116.90
Purchase #6	$172.47	4.333%	$179.9431	$179.94	$179.95	$179.90
Purchase #7	$236.30	3.644%	$244.9108	$244.91	$244.90	$244.90
7 purchase totals =	$1,181.57		$1,255.1406	$1,255.13	$1,255.05	$1,255.20