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	$183.87	4.286%	$191.7507	$191.75	$191.75	$191.80
Purchase #2	$53.37	5.392%	$56.2477	$56.25	$56.25	$56.20
Purchase #3	$46.70	11.442%	$52.0434	$52.04	$52.05	$52.00
Purchase #4	$152.27	8.155%	$164.6876	$164.69	$164.70	$164.70
Purchase #5	$217.49	4.550%	$227.3858	$227.39	$227.40	$227.40
Purchase #6	$216.46	5.123%	$227.5492	$227.55	$227.55	$227.50
Purchase #7	$206.99	4.797%	$216.9193	$216.92	$216.90	$216.90
7 purchase totals =	$1,077.15		$1,136.5837	$1,136.59	$1,136.60	$1,136.50