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	$102.83	8.200%	$111.2621	$111.26	$111.25	$111.30
Purchase #2	$16.74	5.236%	$17.6165	$17.62	$17.60	$17.60
Purchase #3	$248.59	10.856%	$275.5769	$275.58	$275.60	$275.60
Purchase #4	$183.61	4.524%	$191.9165	$191.92	$191.90	$191.90
Purchase #5	$208.97	5.397%	$220.2481	$220.25	$220.25	$220.20
Purchase #6	$186.25	5.467%	$196.4323	$196.43	$196.45	$196.40
Purchase #7	$18.83	8.489%	$20.4285	$20.43	$20.45	$20.40
7 purchase totals =	$965.82		$1,033.4809	$1,033.49	$1,033.50	$1,033.40