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	$67.39	8.148%	$72.8809	$72.88	$72.90	$72.90
Purchase #2	$74.95	8.150%	$81.0584	$81.06	$81.05	$81.10
Purchase #3	$128.78	3.152%	$132.8391	$132.84	$132.85	$132.80
Purchase #4	$90.96	10.756%	$100.7437	$100.74	$100.75	$100.70
Purchase #5	$190.59	5.639%	$201.3374	$201.34	$201.35	$201.30
Purchase #6	$198.60	6.704%	$211.9141	$211.91	$211.90	$211.90
Purchase #7	$82.43	5.384%	$86.868	$86.87	$86.85	$86.90
7 purchase totals =	$833.70		$887.6416	$887.64	$887.65	$887.60