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	$110.42	7.715%	$118.9389	$118.94	$118.95	$118.90
Purchase #2	$168.90	7.418%	$181.429	$181.43	$181.45	$181.40
Purchase #3	$186.93	9.417%	$204.5332	$204.53	$204.55	$204.50
Purchase #4	$62.81	9.579%	$68.8266	$68.83	$68.85	$68.80
Purchase #5	$125.61	11.131%	$139.5916	$139.59	$139.60	$139.60
Purchase #6	$100.27	13.150%	$113.4555	$113.46	$113.45	$113.50
Purchase #7	$204.65	10.160%	$225.4424	$225.44	$225.45	$225.40
7 purchase totals =	$959.59		$1,052.2172	$1,052.22	$1,052.30	$1,052.10