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	$225.95	4.355%	$235.7901	$235.79	$235.80	$235.80
Purchase #2	$143.56	5.218%	$151.051	$151.05	$151.05	$151.10
Purchase #3	$17.76	3.578%	$18.3955	$18.40	$18.40	$18.40
Purchase #4	$208.61	4.742%	$218.5023	$218.50	$218.50	$218.50
Purchase #5	$131.45	8.805%	$143.0242	$143.02	$143.00	$143.00
Purchase #6	$101.92	10.850%	$112.9783	$112.98	$113.00	$113.00
Purchase #7	$171.52	5.738%	$181.3618	$181.36	$181.35	$181.40
7 purchase totals =	$1,000.77		$1,061.1032	$1,061.10	$1,061.10	$1,061.20