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	$63.38	3.216%	$65.4183	$65.42	$65.40	$65.40
Purchase #2	$55.31	11.549%	$61.6978	$61.70	$61.70	$61.70
Purchase #3	$103.72	4.411%	$108.2951	$108.30	$108.30	$108.30
Purchase #4	$104.70	7.563%	$112.6185	$112.62	$112.60	$112.60
Purchase #5	$145.47	3.569%	$150.6618	$150.66	$150.65	$150.70
Purchase #6	$194.55	5.716%	$205.6705	$205.67	$205.65	$205.70
Purchase #7	$188.54	4.425%	$196.8829	$196.88	$196.90	$196.90
7 purchase totals =	$855.67		$901.2449	$901.25	$901.20	$901.30