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	$176.37	8.334%	$191.0687	$191.07	$191.05	$191.10
Purchase #2	$125.87	13.181%	$142.4609	$142.46	$142.45	$142.50
Purchase #3	$196.32	11.856%	$219.5957	$219.60	$219.60	$219.60
Purchase #4	$6.59	8.498%	$7.15	$7.15	$7.15	$7.20
Purchase #5	$166.97	9.821%	$183.3681	$183.37	$183.35	$183.40
Purchase #6	$185.95	5.351%	$195.9002	$195.90	$195.90	$195.90
Purchase #7	$69.94	3.126%	$72.1263	$72.13	$72.15	$72.10
7 purchase totals =	$928.01		$1,011.6699	$1,011.68	$1,011.65	$1,011.80