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	$188.43	10.672%	$208.5392	$208.54	$208.55	$208.50
Purchase #2	$151.61	11.638%	$169.2544	$169.25	$169.25	$169.30
Purchase #3	$44.37	3.501%	$45.9234	$45.92	$45.90	$45.90
Purchase #4	$39.73	9.778%	$43.6148	$43.61	$43.60	$43.60
Purchase #5	$68.69	10.390%	$75.8269	$75.83	$75.85	$75.80
Purchase #6	$174.85	12.623%	$196.9213	$196.92	$196.90	$196.90
Purchase #7	$137.93	3.391%	$142.6072	$142.61	$142.60	$142.60
7 purchase totals =	$805.61		$882.6872	$882.68	$882.65	$882.60