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	$247.94	8.624%	$269.3223	$269.32	$269.30	$269.30
Purchase #2	$40.40	3.828%	$41.9465	$41.95	$41.95	$41.90
Purchase #3	$162.87	8.437%	$176.6113	$176.61	$176.60	$176.60
Purchase #4	$153.62	8.518%	$166.7054	$166.71	$166.70	$166.70
Purchase #5	$184.56	3.400%	$190.835	$190.84	$190.85	$190.80
Purchase #6	$11.58	5.142%	$12.1754	$12.18	$12.20	$12.20
Purchase #7	$146.95	8.780%	$159.8522	$159.85	$159.85	$159.90
7 purchase totals =	$947.92		$1,017.4481	$1,017.46	$1,017.45	$1,017.40