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	$58.65	3.477%	$60.6893	$60.69	$60.70	$60.70
Purchase #2	$113.93	11.368%	$126.8816	$126.88	$126.90	$126.90
Purchase #3	$67.88	9.815%	$74.5424	$74.54	$74.55	$74.50
Purchase #4	$84.60	5.708%	$89.429	$89.43	$89.45	$89.40
Purchase #5	$95.48	5.225%	$100.4688	$100.47	$100.45	$100.50
Purchase #6	$110.75	12.213%	$124.2759	$124.28	$124.30	$124.30
Purchase #7	$135.72	8.231%	$146.8911	$146.89	$146.90	$146.90
7 purchase totals =	$667.01		$723.1781	$723.18	$723.25	$723.20