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	$198.81	7.569%	$213.8579	$213.86	$213.85	$213.90
Purchase #2	$119.47	12.629%	$134.5579	$134.56	$134.55	$134.60
Purchase #3	$204.43	9.317%	$223.4767	$223.48	$223.50	$223.50
Purchase #4	$42.73	9.858%	$46.9423	$46.94	$46.95	$46.90
Purchase #5	$98.55	9.611%	$108.0216	$108.02	$108.00	$108.00
Purchase #6	$94.37	5.230%	$99.3056	$99.31	$99.30	$99.30
Purchase #7	$98.86	3.631%	$102.4496	$102.45	$102.45	$102.40
7 purchase totals =	$857.22		$928.6116	$928.62	$928.60	$928.60