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	$84.78	13.874%	$96.5424	$96.54	$96.55	$96.50
Purchase #2	$159.58	12.394%	$179.3583	$179.36	$179.35	$179.40
Purchase #3	$243.45	5.185%	$256.0729	$256.07	$256.05	$256.10
Purchase #4	$119.93	9.525%	$131.3533	$131.35	$131.35	$131.40
Purchase #5	$48.47	6.269%	$51.5086	$51.51	$51.50	$51.50
Purchase #6	$160.83	9.665%	$176.3742	$176.37	$176.35	$176.40
Purchase #7	$63.70	12.411%	$71.6058	$71.61	$71.60	$71.60
7 purchase totals =	$880.74		$962.8155	$962.81	$962.75	$962.90