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	$200.48	5.654%	$211.8151	$211.82	$211.80	$211.80
Purchase #2	$12.82	8.316%	$13.8861	$13.89	$13.90	$13.90
Purchase #3	$69.78	4.244%	$72.7415	$72.74	$72.75	$72.70
Purchase #4	$156.80	9.471%	$171.6505	$171.65	$171.65	$171.70
Purchase #5	$174.56	12.233%	$195.9139	$195.91	$195.90	$195.90
Purchase #6	$134.37	7.518%	$144.4719	$144.47	$144.45	$144.50
Purchase #7	$59.78	5.584%	$63.1181	$63.12	$63.10	$63.10
7 purchase totals =	$808.59		$873.5971	$873.60	$873.55	$873.60