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	$152.69	11.117%	$169.6645	$169.66	$169.65	$169.70
Purchase #2	$212.54	7.505%	$228.4911	$228.49	$228.50	$228.50
Purchase #3	$133.34	3.369%	$137.8322	$137.83	$137.85	$137.80
Purchase #4	$100.83	7.584%	$108.4769	$108.48	$108.50	$108.50
Purchase #5	$176.77	3.112%	$182.2711	$182.27	$182.25	$182.30
Purchase #6	$139.73	4.236%	$145.649	$145.65	$145.65	$145.60
Purchase #7	$208.84	7.256%	$223.9934	$223.99	$224.00	$224.00
7 purchase totals =	$1,124.74		$1,196.3782	$1,196.37	$1,196.40	$1,196.40