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	$118.31	11.511%	$131.9287	$131.93	$131.95	$131.90
Purchase #2	$240.31	13.196%	$272.0213	$272.02	$272.00	$272.00
Purchase #3	$86.52	7.288%	$92.8256	$92.83	$92.85	$92.80
Purchase #4	$68.58	4.487%	$71.6572	$71.66	$71.65	$71.70
Purchase #5	$132.65	7.511%	$142.6133	$142.61	$142.60	$142.60
Purchase #6	$200.79	11.196%	$223.2704	$223.27	$223.25	$223.30
Purchase #7	$164.50	12.293%	$184.722	$184.72	$184.70	$184.70
7 purchase totals =	$1,011.66		$1,119.0385	$1,119.04	$1,119.00	$1,119.00