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	$174.94	13.694%	$198.8963	$198.90	$198.90	$198.90
Purchase #2	$21.84	4.194%	$22.756	$22.76	$22.75	$22.80
Purchase #3	$112.71	11.693%	$125.8892	$125.89	$125.90	$125.90
Purchase #4	$146.65	3.402%	$151.639	$151.64	$151.65	$151.60
Purchase #5	$224.42	13.686%	$255.1341	$255.13	$255.15	$255.10
Purchase #6	$172.61	4.859%	$180.9971	$181.00	$181.00	$181.00
Purchase #7	$216.72	13.116%	$245.145	$245.15	$245.15	$245.10
7 purchase totals =	$1,069.89		$1,180.4567	$1,180.47	$1,180.50	$1,180.40