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	$216.92	4.856%	$227.4536	$227.45	$227.45	$227.50
Purchase #2	$174.94	3.573%	$181.1906	$181.19	$181.20	$181.20
Purchase #3	$49.95	5.196%	$52.5454	$52.55	$52.55	$52.50
Purchase #4	$111.46	6.400%	$118.5934	$118.59	$118.60	$118.60
Purchase #5	$91.44	3.148%	$94.3185	$94.32	$94.30	$94.30
Purchase #6	$215.94	8.334%	$233.9364	$233.94	$233.95	$233.90
Purchase #7	$124.96	9.541%	$136.8824	$136.88	$136.90	$136.90
7 purchase totals =	$985.61		$1,044.9203	$1,044.92	$1,044.95	$1,044.90