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	$173.27	13.535%	$196.7221	$196.72	$196.70	$196.70
Purchase #2	$24.82	13.617%	$28.1997	$28.20	$28.20	$28.20
Purchase #3	$37.74	8.510%	$40.9517	$40.95	$40.95	$41.00
Purchase #4	$228.85	13.412%	$259.5434	$259.54	$259.55	$259.50
Purchase #5	$48.66	5.730%	$51.4482	$51.45	$51.45	$51.40
Purchase #6	$189.88	3.558%	$196.6359	$196.64	$196.65	$196.60
Purchase #7	$113.33	7.223%	$121.5158	$121.52	$121.50	$121.50
7 purchase totals =	$816.55		$895.0168	$895.02	$895.00	$894.90