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	$209.96	11.241%	$233.5616	$233.56	$233.55	$233.60
Purchase #2	$98.67	3.708%	$102.3287	$102.33	$102.35	$102.30
Purchase #3	$218.90	10.503%	$241.8911	$241.89	$241.90	$241.90
Purchase #4	$248.51	9.761%	$272.7671	$272.77	$272.75	$272.80
Purchase #5	$70.32	11.303%	$78.2683	$78.27	$78.25	$78.30
Purchase #6	$49.66	12.478%	$55.8566	$55.86	$55.85	$55.90
Purchase #7	$199.61	4.246%	$208.0854	$208.09	$208.10	$208.10
7 purchase totals =	$1,095.63		$1,192.7588	$1,192.77	$1,192.75	$1,192.90