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	$101.67	4.178%	$105.9178	$105.92	$105.90	$105.90
Purchase #2	$189.65	5.865%	$200.773	$200.77	$200.75	$200.80
Purchase #3	$93.80	7.740%	$101.0601	$101.06	$101.05	$101.10
Purchase #4	$10.40	11.570%	$11.6033	$11.60	$11.60	$11.60
Purchase #5	$119.82	6.270%	$127.3327	$127.33	$127.35	$127.30
Purchase #6	$212.83	13.614%	$241.8047	$241.80	$241.80	$241.80
Purchase #7	$205.72	7.727%	$221.616	$221.62	$221.60	$221.60
7 purchase totals =	$933.89		$1,010.1076	$1,010.10	$1,010.05	$1,010.10