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	$69.79	9.560%	$76.4619	$76.46	$76.45	$76.50
Purchase #2	$228.81	7.349%	$245.6252	$245.63	$245.65	$245.60
Purchase #3	$119.74	7.588%	$128.8259	$128.83	$128.85	$128.80
Purchase #4	$69.76	12.483%	$78.4681	$78.47	$78.45	$78.50
Purchase #5	$244.35	4.535%	$255.4313	$255.43	$255.45	$255.40
Purchase #6	$91.25	4.146%	$95.0332	$95.03	$95.05	$95.00
Purchase #7	$57.59	9.498%	$63.0599	$63.06	$63.05	$63.10
7 purchase totals =	$881.29		$942.9055	$942.91	$942.95	$942.90