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	$94.82	7.346%	$101.7855	$101.79	$101.80	$101.80
Purchase #2	$72.74	8.359%	$78.8203	$78.82	$78.80	$78.80
Purchase #3	$213.83	4.204%	$222.8194	$222.82	$222.80	$222.80
Purchase #4	$31.85	13.647%	$36.1966	$36.20	$36.20	$36.20
Purchase #5	$238.48	10.455%	$263.4131	$263.41	$263.40	$263.40
Purchase #6	$228.64	5.426%	$241.046	$241.05	$241.05	$241.00
Purchase #7	$139.30	13.144%	$157.6096	$157.61	$157.60	$157.60
7 purchase totals =	$1,019.66		$1,101.6905	$1,101.70	$1,101.65	$1,101.60