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	$224.82	8.550%	$244.0421	$244.04	$244.05	$244.00
Purchase #2	$69.73	10.208%	$76.848	$76.85	$76.85	$76.80
Purchase #3	$7.39	3.312%	$7.6348	$7.63	$7.65	$7.60
Purchase #4	$190.26	13.611%	$216.1563	$216.16	$216.15	$216.20
Purchase #5	$89.66	12.294%	$100.6828	$100.68	$100.70	$100.70
Purchase #6	$78.96	4.836%	$82.7785	$82.78	$82.80	$82.80
Purchase #7	$123.63	11.159%	$137.4259	$137.43	$137.45	$137.40
7 purchase totals =	$784.45		$865.5684	$865.57	$865.65	$865.50