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	$112.78	11.776%	$126.061	$126.06	$126.05	$126.10
Purchase #2	$160.93	9.113%	$175.5956	$175.60	$175.60	$175.60
Purchase #3	$242.50	11.699%	$270.8701	$270.87	$270.85	$270.90
Purchase #4	$59.61	7.200%	$63.9019	$63.90	$63.90	$63.90
Purchase #5	$131.62	8.190%	$142.3997	$142.40	$142.40	$142.40
Purchase #6	$6.53	7.742%	$7.0356	$7.04	$7.05	$7.00
Purchase #7	$191.55	13.104%	$216.6507	$216.65	$216.65	$216.70
7 purchase totals =	$905.52		$1,002.5146	$1,002.52	$1,002.50	$1,002.60