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	$142.52	7.112%	$152.656	$152.66	$152.65	$152.70
Purchase #2	$84.57	7.327%	$90.7664	$90.77	$90.75	$90.80
Purchase #3	$160.54	8.342%	$173.9322	$173.93	$173.95	$173.90
Purchase #4	$122.81	12.260%	$137.8665	$137.87	$137.85	$137.90
Purchase #5	$230.25	6.818%	$245.9484	$245.95	$245.95	$245.90
Purchase #6	$176.57	11.283%	$196.4924	$196.49	$196.50	$196.50
Purchase #7	$8.91	10.555%	$9.8505	$9.85	$9.85	$9.90
7 purchase totals =	$926.17		$1,007.5124	$1,007.52	$1,007.50	$1,007.60