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	$209.78	3.712%	$217.567	$217.57	$217.55	$217.60
Purchase #2	$164.52	10.279%	$181.431	$181.43	$181.45	$181.40
Purchase #3	$54.46	12.661%	$61.3552	$61.36	$61.35	$61.40
Purchase #4	$45.90	13.407%	$52.0538	$52.05	$52.05	$52.10
Purchase #5	$100.49	10.568%	$111.1098	$111.11	$111.10	$111.10
Purchase #6	$129.30	6.513%	$137.7213	$137.72	$137.70	$137.70
Purchase #7	$168.35	8.300%	$182.3231	$182.32	$182.30	$182.30
7 purchase totals =	$872.80		$943.5612	$943.56	$943.50	$943.60