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	$206.82	8.817%	$225.0553	$225.06	$225.05	$225.10
Purchase #2	$58.29	12.473%	$65.5605	$65.56	$65.55	$65.60
Purchase #3	$11.42	10.148%	$12.5789	$12.58	$12.60	$12.60
Purchase #4	$66.88	5.803%	$70.761	$70.76	$70.75	$70.80
Purchase #5	$120.79	5.390%	$127.3006	$127.30	$127.30	$127.30
Purchase #6	$136.54	12.469%	$153.5652	$153.57	$153.55	$153.60
Purchase #7	$44.64	6.376%	$47.4862	$47.49	$47.50	$47.50
7 purchase totals =	$645.38		$702.3077	$702.32	$702.30	$702.50