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	$185.32	5.584%	$195.6683	$195.67	$195.65	$195.70
Purchase #2	$155.47	4.242%	$162.065	$162.07	$162.05	$162.10
Purchase #3	$59.82	13.208%	$67.721	$67.72	$67.70	$67.70
Purchase #4	$118.58	7.555%	$127.5387	$127.54	$127.55	$127.50
Purchase #5	$67.42	12.686%	$75.9729	$75.97	$75.95	$76.00
Purchase #6	$77.42	6.157%	$82.1867	$82.19	$82.20	$82.20
Purchase #7	$198.31	5.152%	$208.5269	$208.53	$208.55	$208.50
7 purchase totals =	$862.34		$919.6795	$919.69	$919.65	$919.70