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	$192.36	11.414%	$214.316	$214.32	$214.30	$214.30
Purchase #2	$188.71	4.322%	$196.866	$196.87	$196.85	$196.90
Purchase #3	$169.39	12.384%	$190.3673	$190.37	$190.35	$190.40
Purchase #4	$89.54	9.350%	$97.912	$97.91	$97.90	$97.90
Purchase #5	$146.97	8.474%	$159.4242	$159.42	$159.40	$159.40
Purchase #6	$52.71	8.193%	$57.0285	$57.03	$57.05	$57.00
Purchase #7	$138.30	9.857%	$151.9322	$151.93	$151.95	$151.90
7 purchase totals =	$977.98		$1,067.8462	$1,067.85	$1,067.80	$1,067.80