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	$224.62	6.336%	$238.8519	$238.85	$238.85	$238.90
Purchase #2	$69.67	3.732%	$72.2701	$72.27	$72.25	$72.30
Purchase #3	$93.55	12.606%	$105.3429	$105.34	$105.35	$105.30
Purchase #4	$150.80	9.528%	$165.1682	$165.17	$165.15	$165.20
Purchase #5	$238.68	6.424%	$254.0128	$254.01	$254.00	$254.00
Purchase #6	$100.72	5.809%	$106.5708	$106.57	$106.55	$106.60
Purchase #7	$141.84	10.263%	$156.397	$156.40	$156.40	$156.40
7 purchase totals =	$1,019.88		$1,098.6137	$1,098.61	$1,098.55	$1,098.70