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	$86.34	9.370%	$94.4301	$94.43	$94.45	$94.40
Purchase #2	$87.78	8.302%	$95.0675	$95.07	$95.05	$95.10
Purchase #3	$135.90	8.776%	$147.8266	$147.83	$147.85	$147.80
Purchase #4	$232.41	4.772%	$243.5006	$243.50	$243.50	$243.50
Purchase #5	$101.37	10.384%	$111.8963	$111.90	$111.90	$111.90
Purchase #6	$191.43	8.383%	$207.4776	$207.48	$207.50	$207.50
Purchase #7	$238.60	9.342%	$260.89	$260.89	$260.90	$260.90
7 purchase totals =	$1,073.83		$1,161.0887	$1,161.10	$1,161.15	$1,161.10