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	$64.95	5.603%	$68.5891	$68.59	$68.60	$68.60
Purchase #2	$164.27	10.756%	$181.9389	$181.94	$181.95	$181.90
Purchase #3	$69.58	3.305%	$71.8796	$71.88	$71.90	$71.90
Purchase #4	$34.90	7.788%	$37.618	$37.62	$37.60	$37.60
Purchase #5	$112.89	9.181%	$123.2544	$123.25	$123.25	$123.30
Purchase #6	$165.35	3.738%	$171.5308	$171.53	$171.55	$171.50
Purchase #7	$203.71	8.295%	$220.6077	$220.61	$220.60	$220.60
7 purchase totals =	$815.65		$875.4185	$875.42	$875.45	$875.40