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	$151.95	5.465%	$160.2541	$160.25	$160.25	$160.30
Purchase #2	$187.81	3.215%	$193.8481	$193.85	$193.85	$193.80
Purchase #3	$21.92	7.205%	$23.4993	$23.50	$23.50	$23.50
Purchase #4	$172.85	9.158%	$188.6796	$188.68	$188.70	$188.70
Purchase #5	$168.54	10.536%	$186.2974	$186.30	$186.30	$186.30
Purchase #6	$134.31	6.856%	$143.5183	$143.52	$143.50	$143.50
Purchase #7	$110.41	11.865%	$123.5101	$123.51	$123.50	$123.50
7 purchase totals =	$947.79		$1,019.6069	$1,019.61	$1,019.60	$1,019.60