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	$220.82	9.736%	$242.319	$242.32	$242.30	$242.30
Purchase #2	$40.53	3.432%	$41.921	$41.92	$41.90	$41.90
Purchase #3	$220.83	3.506%	$228.5723	$228.57	$228.55	$228.60
Purchase #4	$81.32	9.562%	$89.0958	$89.10	$89.10	$89.10
Purchase #5	$118.53	13.770%	$134.8516	$134.85	$134.85	$134.90
Purchase #6	$10.27	12.834%	$11.5881	$11.59	$11.60	$11.60
Purchase #7	$184.91	11.228%	$205.6717	$205.67	$205.65	$205.70
7 purchase totals =	$877.21		$954.0195	$954.02	$953.95	$954.10