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	$211.83	7.707%	$228.1557	$228.16	$228.15	$228.20
Purchase #2	$81.51	4.821%	$85.4396	$85.44	$85.45	$85.40
Purchase #3	$133.87	11.260%	$148.9438	$148.94	$148.95	$148.90
Purchase #4	$91.85	9.561%	$100.6318	$100.63	$100.65	$100.60
Purchase #5	$101.26	12.676%	$114.0957	$114.10	$114.10	$114.10
Purchase #6	$178.35	11.301%	$198.5053	$198.51	$198.50	$198.50
Purchase #7	$174.40	6.568%	$185.8546	$185.85	$185.85	$185.90
7 purchase totals =	$973.07		$1,061.6265	$1,061.63	$1,061.65	$1,061.60