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	$183.37	9.454%	$200.7058	$200.71	$200.70	$200.70
Purchase #2	$122.29	12.618%	$137.7206	$137.72	$137.70	$137.70
Purchase #3	$29.43	5.389%	$31.016	$31.02	$31.00	$31.00
Purchase #4	$148.35	11.452%	$165.339	$165.34	$165.35	$165.30
Purchase #5	$211.29	12.678%	$238.0773	$238.08	$238.10	$238.10
Purchase #6	$125.74	8.401%	$136.3034	$136.30	$136.30	$136.30
Purchase #7	$249.57	5.321%	$262.8496	$262.85	$262.85	$262.80
7 purchase totals =	$1,070.04		$1,172.0117	$1,172.02	$1,172.00	$1,171.90