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	$195.84	9.638%	$214.7151	$214.72	$214.70	$214.70
Purchase #2	$28.55	7.179%	$30.5996	$30.60	$30.60	$30.60
Purchase #3	$60.63	8.172%	$65.5847	$65.58	$65.60	$65.60
Purchase #4	$140.38	5.617%	$148.2651	$148.27	$148.25	$148.30
Purchase #5	$48.85	13.817%	$55.5996	$55.60	$55.60	$55.60
Purchase #6	$238.64	9.613%	$261.5805	$261.58	$261.60	$261.60
Purchase #7	$242.27	5.213%	$254.8995	$254.90	$254.90	$254.90
7 purchase totals =	$955.16		$1,031.2441	$1,031.25	$1,031.25	$1,031.30