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	$57.31	3.694%	$59.427	$59.43	$59.45	$59.40
Purchase #2	$78.81	9.239%	$86.0913	$86.09	$86.10	$86.10
Purchase #3	$174.92	7.271%	$187.6384	$187.64	$187.65	$187.60
Purchase #4	$182.38	3.286%	$188.373	$188.37	$188.35	$188.40
Purchase #5	$99.73	10.152%	$109.8546	$109.85	$109.85	$109.90
Purchase #6	$151.89	11.755%	$169.7447	$169.74	$169.75	$169.70
Purchase #7	$144.71	5.754%	$153.0366	$153.04	$153.05	$153.00
7 purchase totals =	$889.75		$954.1656	$954.16	$954.20	$954.10