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	$168.53	8.249%	$182.432	$182.43	$182.45	$182.40
Purchase #2	$205.32	4.788%	$215.1507	$215.15	$215.15	$215.20
Purchase #3	$112.83	6.574%	$120.2474	$120.25	$120.25	$120.20
Purchase #4	$68.70	13.659%	$78.0837	$78.08	$78.10	$78.10
Purchase #5	$239.97	6.222%	$254.9009	$254.90	$254.90	$254.90
Purchase #6	$59.78	11.423%	$66.6087	$66.61	$66.60	$66.60
Purchase #7	$110.33	13.841%	$125.6008	$125.60	$125.60	$125.60
7 purchase totals =	$965.46		$1,043.0242	$1,043.02	$1,043.05	$1,043.00