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	$224.71	8.561%	$243.9474	$243.95	$243.95	$243.90
Purchase #2	$82.80	9.821%	$90.9318	$90.93	$90.95	$90.90
Purchase #3	$47.76	3.232%	$49.3036	$49.30	$49.30	$49.30
Purchase #4	$32.91	5.430%	$34.697	$34.70	$34.70	$34.70
Purchase #5	$187.58	4.804%	$196.5913	$196.59	$196.60	$196.60
Purchase #6	$19.63	7.443%	$21.0911	$21.09	$21.10	$21.10
Purchase #7	$82.61	8.238%	$89.4154	$89.42	$89.40	$89.40
7 purchase totals =	$678.00		$725.9776	$725.98	$726.00	$725.90