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	$108.54	3.455%	$112.2901	$112.29	$112.30	$112.30
Purchase #2	$204.78	10.380%	$226.0362	$226.04	$226.05	$226.00
Purchase #3	$37.83	12.617%	$42.603	$42.60	$42.60	$42.60
Purchase #4	$222.97	11.553%	$248.7297	$248.73	$248.75	$248.70
Purchase #5	$120.25	12.172%	$134.8868	$134.89	$134.90	$134.90
Purchase #6	$182.93	3.820%	$189.9179	$189.92	$189.90	$189.90
Purchase #7	$143.50	6.256%	$152.4774	$152.48	$152.50	$152.50
7 purchase totals =	$1,020.80		$1,106.9411	$1,106.95	$1,107.00	$1,106.90