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	$195.42	9.439%	$213.8657	$213.87	$213.85	$213.90
Purchase #2	$60.96	5.735%	$64.4561	$64.46	$64.45	$64.50
Purchase #3	$119.41	7.281%	$128.1042	$128.10	$128.10	$128.10
Purchase #4	$41.78	3.740%	$43.3426	$43.34	$43.35	$43.30
Purchase #5	$95.81	5.318%	$100.9052	$100.91	$100.90	$100.90
Purchase #6	$196.64	6.479%	$209.3803	$209.38	$209.40	$209.40
Purchase #7	$157.90	9.510%	$172.9163	$172.92	$172.90	$172.90
7 purchase totals =	$867.92		$932.9704	$932.98	$932.95	$933.00