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	$177.50	10.847%	$196.7534	$196.75	$196.75	$196.80
Purchase #2	$206.61	6.828%	$220.7173	$220.72	$220.70	$220.70
Purchase #3	$162.99	12.650%	$183.6082	$183.61	$183.60	$183.60
Purchase #4	$6.34	11.144%	$7.0465	$7.05	$7.05	$7.00
Purchase #5	$172.90	13.853%	$196.8518	$196.85	$196.85	$196.90
Purchase #6	$113.34	13.681%	$128.846	$128.85	$128.85	$128.80
Purchase #7	$166.26	8.661%	$180.6598	$180.66	$180.65	$180.70
7 purchase totals =	$1,005.94		$1,114.4830	$1,114.49	$1,114.45	$1,114.50