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	$162.54	10.363%	$179.384	$179.38	$179.40	$179.40
Purchase #2	$155.67	10.273%	$171.662	$171.66	$171.65	$171.70
Purchase #3	$83.78	3.570%	$86.7709	$86.77	$86.75	$86.80
Purchase #4	$139.35	4.112%	$145.0801	$145.08	$145.10	$145.10
Purchase #5	$91.30	7.179%	$97.8544	$97.85	$97.85	$97.90
Purchase #6	$238.63	5.318%	$251.3203	$251.32	$251.30	$251.30
Purchase #7	$143.46	7.647%	$154.4304	$154.43	$154.45	$154.40
7 purchase totals =	$1,014.73		$1,086.5021	$1,086.49	$1,086.50	$1,086.60