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	$169.62	4.188%	$176.7237	$176.72	$176.70	$176.70
Purchase #2	$98.82	8.164%	$106.8877	$106.89	$106.90	$106.90
Purchase #3	$140.65	7.640%	$151.3957	$151.40	$151.40	$151.40
Purchase #4	$215.26	7.123%	$230.593	$230.59	$230.60	$230.60
Purchase #5	$193.83	11.770%	$216.6438	$216.64	$216.65	$216.60
Purchase #6	$174.54	6.460%	$185.8153	$185.82	$185.80	$185.80
Purchase #7	$50.28	12.398%	$56.5137	$56.51	$56.50	$56.50
7 purchase totals =	$1,043.00		$1,124.5729	$1,124.57	$1,124.55	$1,124.50