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	$55.89	11.686%	$62.4213	$62.42	$62.40	$62.40
Purchase #2	$35.39	9.271%	$38.671	$38.67	$38.65	$38.70
Purchase #3	$140.58	7.727%	$151.4426	$151.44	$151.45	$151.40
Purchase #4	$136.44	10.742%	$151.0964	$151.10	$151.10	$151.10
Purchase #5	$101.28	10.563%	$111.9782	$111.98	$112.00	$112.00
Purchase #6	$205.48	13.647%	$233.5219	$233.52	$233.50	$233.50
Purchase #7	$181.79	9.782%	$199.5727	$199.57	$199.55	$199.60
7 purchase totals =	$856.85		$948.7041	$948.70	$948.65	$948.70