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	$54.93	13.410%	$62.2961	$62.30	$62.30	$62.30
Purchase #2	$145.26	4.758%	$152.1715	$152.17	$152.15	$152.20
Purchase #3	$22.30	13.632%	$25.3399	$25.34	$25.35	$25.30
Purchase #4	$34.64	3.457%	$35.8375	$35.84	$35.85	$35.80
Purchase #5	$32.90	8.702%	$35.763	$35.76	$35.75	$35.80
Purchase #6	$104.42	6.652%	$111.366	$111.37	$111.35	$111.40
Purchase #7	$36.26	5.172%	$38.1354	$38.14	$38.15	$38.10
7 purchase totals =	$430.71		$460.9094	$460.92	$460.90	$460.90