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	$59.43	4.855%	$62.3153	$62.32	$62.30	$62.30
Purchase #2	$100.40	9.429%	$109.8667	$109.87	$109.85	$109.90
Purchase #3	$162.62	9.571%	$178.1844	$178.18	$178.20	$178.20
Purchase #4	$184.40	11.328%	$205.2888	$205.29	$205.30	$205.30
Purchase #5	$46.35	9.301%	$50.661	$50.66	$50.65	$50.70
Purchase #6	$200.74	7.360%	$215.5145	$215.51	$215.50	$215.50
Purchase #7	$176.69	7.239%	$189.4806	$189.48	$189.50	$189.50
7 purchase totals =	$930.63		$1,011.3113	$1,011.31	$1,011.30	$1,011.40