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	$152.82	9.595%	$167.4831	$167.48	$167.50	$167.50
Purchase #2	$228.58	4.406%	$238.6512	$238.65	$238.65	$238.70
Purchase #3	$18.87	6.691%	$20.1326	$20.13	$20.15	$20.10
Purchase #4	$67.69	6.713%	$72.234	$72.23	$72.25	$72.20
Purchase #5	$58.94	8.143%	$63.7395	$63.74	$63.75	$63.70
Purchase #6	$216.34	9.334%	$236.5332	$236.53	$236.55	$236.50
Purchase #7	$218.92	3.401%	$226.3655	$226.37	$226.35	$226.40
7 purchase totals =	$962.16		$1,025.1391	$1,025.13	$1,025.20	$1,025.10