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	$202.95	8.198%	$219.5878	$219.59	$219.60	$219.60
Purchase #2	$75.61	8.622%	$82.1291	$82.13	$82.15	$82.10
Purchase #3	$112.64	13.449%	$127.789	$127.79	$127.80	$127.80
Purchase #4	$40.89	13.605%	$46.4531	$46.45	$46.45	$46.50
Purchase #5	$85.64	11.154%	$95.1923	$95.19	$95.20	$95.20
Purchase #6	$52.88	8.356%	$57.2987	$57.30	$57.30	$57.30
Purchase #7	$157.54	9.828%	$173.023	$173.02	$173.00	$173.00
7 purchase totals =	$728.15		$801.4730	$801.47	$801.50	$801.50