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	$160.51	7.691%	$172.8548	$172.85	$172.85	$172.90
Purchase #2	$7.26	9.378%	$7.9408	$7.94	$7.95	$7.90
Purchase #3	$64.47	6.173%	$68.4497	$68.45	$68.45	$68.40
Purchase #4	$147.32	6.115%	$156.3286	$156.33	$156.35	$156.30
Purchase #5	$210.59	9.113%	$229.7811	$229.78	$229.80	$229.80
Purchase #6	$250.42	13.560%	$284.377	$284.38	$284.40	$284.40
Purchase #7	$213.90	12.716%	$241.0995	$241.10	$241.10	$241.10
7 purchase totals =	$1,054.47		$1,160.8315	$1,160.83	$1,160.90	$1,160.80