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	$196.83	13.838%	$224.0673	$224.07	$224.05	$224.10
Purchase #2	$242.34	4.398%	$252.9981	$253.00	$253.00	$253.00
Purchase #3	$56.39	5.554%	$59.5219	$59.52	$59.50	$59.50
Purchase #4	$205.68	4.684%	$215.3141	$215.31	$215.30	$215.30
Purchase #5	$44.41	7.570%	$47.7718	$47.77	$47.75	$47.80
Purchase #6	$168.49	9.236%	$184.0517	$184.05	$184.05	$184.10
Purchase #7	$91.44	11.419%	$101.8815	$101.88	$101.90	$101.90
7 purchase totals =	$1,005.58		$1,085.6064	$1,085.60	$1,085.55	$1,085.70