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	$46.42	13.254%	$52.5725	$52.57	$52.55	$52.60
Purchase #2	$12.77	5.550%	$13.4787	$13.48	$13.50	$13.50
Purchase #3	$65.26	3.108%	$67.2883	$67.29	$67.30	$67.30
Purchase #4	$61.55	9.734%	$67.5413	$67.54	$67.55	$67.50
Purchase #5	$211.80	3.384%	$218.9673	$218.97	$218.95	$219.00
Purchase #6	$91.63	9.632%	$100.4558	$100.46	$100.45	$100.50
Purchase #7	$92.57	3.733%	$96.0256	$96.03	$96.05	$96.00
7 purchase totals =	$582.00		$616.3295	$616.34	$616.35	$616.40