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	$208.50	11.179%	$231.8082	$231.81	$231.80	$231.80
Purchase #2	$164.46	13.375%	$186.4565	$186.46	$186.45	$186.50
Purchase #3	$153.42	12.367%	$172.3935	$172.39	$172.40	$172.40
Purchase #4	$127.84	11.198%	$142.1555	$142.16	$142.15	$142.20
Purchase #5	$229.87	11.616%	$256.5717	$256.57	$256.55	$256.60
Purchase #6	$214.94	7.757%	$231.6129	$231.61	$231.60	$231.60
Purchase #7	$188.90	10.631%	$208.982	$208.98	$209.00	$209.00
7 purchase totals =	$1,287.93		$1,429.9803	$1,429.98	$1,429.95	$1,430.10