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	$77.52	11.731%	$86.6139	$86.61	$86.60	$86.60
Purchase #2	$123.44	6.608%	$131.5969	$131.60	$131.60	$131.60
Purchase #3	$183.32	4.719%	$191.9709	$191.97	$191.95	$192.00
Purchase #4	$7.95	7.430%	$8.5407	$8.54	$8.55	$8.50
Purchase #5	$119.95	10.461%	$132.498	$132.50	$132.50	$132.50
Purchase #6	$95.63	10.470%	$105.6425	$105.64	$105.65	$105.60
Purchase #7	$136.25	10.678%	$150.7988	$150.80	$150.80	$150.80
7 purchase totals =	$744.06		$807.6617	$807.66	$807.65	$807.60