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	$147.95	6.143%	$157.0386	$157.04	$157.05	$157.00
Purchase #2	$167.51	6.584%	$178.5389	$178.54	$178.55	$178.50
Purchase #3	$5.45	8.172%	$5.8954	$5.90	$5.90	$5.90
Purchase #4	$162.81	12.633%	$183.3778	$183.38	$183.40	$183.40
Purchase #5	$147.75	9.225%	$161.3799	$161.38	$161.40	$161.40
Purchase #6	$207.54	7.185%	$222.4517	$222.45	$222.45	$222.50
Purchase #7	$89.75	12.152%	$100.6564	$100.66	$100.65	$100.70
7 purchase totals =	$928.76		$1,009.3387	$1,009.35	$1,009.40	$1,009.40