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	$174.37	11.523%	$194.4627	$194.46	$194.45	$194.50
Purchase #2	$132.90	10.549%	$146.9196	$146.92	$146.90	$146.90
Purchase #3	$180.70	4.633%	$189.0718	$189.07	$189.05	$189.10
Purchase #4	$156.52	7.369%	$168.054	$168.05	$168.05	$168.10
Purchase #5	$130.81	7.150%	$140.1629	$140.16	$140.15	$140.20
Purchase #6	$137.98	4.667%	$144.4195	$144.42	$144.40	$144.40
Purchase #7	$61.60	7.254%	$66.0685	$66.07	$66.05	$66.10
7 purchase totals =	$974.88		$1,049.1590	$1,049.15	$1,049.05	$1,049.30