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	$78.71	9.182%	$85.9372	$85.94	$85.95	$85.90
Purchase #2	$241.28	7.300%	$258.8934	$258.89	$258.90	$258.90
Purchase #3	$247.37	6.300%	$262.9543	$262.95	$262.95	$263.00
Purchase #4	$162.71	7.253%	$174.5114	$174.51	$174.50	$174.50
Purchase #5	$127.65	5.444%	$134.5993	$134.60	$134.60	$134.60
Purchase #6	$202.44	3.803%	$210.1388	$210.14	$210.15	$210.10
Purchase #7	$36.62	10.375%	$40.4193	$40.42	$40.40	$40.40
7 purchase totals =	$1,096.78		$1,167.4537	$1,167.45	$1,167.45	$1,167.40