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	$177.88	10.176%	$195.9811	$195.98	$196.00	$196.00
Purchase #2	$173.56	6.304%	$184.5012	$184.50	$184.50	$184.50
Purchase #3	$29.52	5.116%	$31.0302	$31.03	$31.05	$31.00
Purchase #4	$177.78	7.724%	$191.5117	$191.51	$191.50	$191.50
Purchase #5	$82.25	4.223%	$85.7234	$85.72	$85.70	$85.70
Purchase #6	$53.32	5.447%	$56.2243	$56.22	$56.20	$56.20
Purchase #7	$19.38	7.162%	$20.768	$20.77	$20.75	$20.80
7 purchase totals =	$713.69		$765.7399	$765.73	$765.70	$765.70