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	$224.40	4.826%	$235.2295	$235.23	$235.25	$235.20
Purchase #2	$203.59	5.321%	$214.423	$214.42	$214.40	$214.40
Purchase #3	$72.32	6.531%	$77.0432	$77.04	$77.05	$77.00
Purchase #4	$198.65	10.338%	$219.1864	$219.19	$219.20	$219.20
Purchase #5	$85.81	10.792%	$95.0706	$95.07	$95.05	$95.10
Purchase #6	$85.35	4.628%	$89.3	$89.30	$89.30	$89.30
Purchase #7	$126.89	12.146%	$142.3021	$142.30	$142.30	$142.30
7 purchase totals =	$997.01		$1,072.5548	$1,072.55	$1,072.55	$1,072.50