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	$196.82	4.811%	$206.289	$206.29	$206.30	$206.30
Purchase #2	$17.69	9.241%	$19.3247	$19.32	$19.30	$19.30
Purchase #3	$19.60	6.390%	$20.8524	$20.85	$20.85	$20.90
Purchase #4	$116.63	13.797%	$132.7214	$132.72	$132.70	$132.70
Purchase #5	$55.73	7.390%	$59.8484	$59.85	$59.85	$59.80
Purchase #6	$140.61	4.138%	$146.4284	$146.43	$146.45	$146.40
Purchase #7	$219.76	12.874%	$248.0519	$248.05	$248.05	$248.10
7 purchase totals =	$766.84		$833.5162	$833.51	$833.50	$833.50