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	$192.95	11.478%	$215.0968	$215.10	$215.10	$215.10
Purchase #2	$82.46	8.332%	$89.3306	$89.33	$89.35	$89.30
Purchase #3	$197.39	11.203%	$219.5036	$219.50	$219.50	$219.50
Purchase #4	$174.28	13.367%	$197.576	$197.58	$197.60	$197.60
Purchase #5	$100.37	12.432%	$112.848	$112.85	$112.85	$112.80
Purchase #6	$46.61	11.559%	$51.9976	$52.00	$52.00	$52.00
Purchase #7	$222.63	11.431%	$248.0788	$248.08	$248.10	$248.10
7 purchase totals =	$1,016.69		$1,134.4314	$1,134.44	$1,134.50	$1,134.40