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	$50.75	5.297%	$53.4382	$53.44	$53.45	$53.40
Purchase #2	$71.96	8.841%	$78.322	$78.32	$78.30	$78.30
Purchase #3	$157.29	3.517%	$162.8219	$162.82	$162.80	$162.80
Purchase #4	$48.77	9.288%	$53.2998	$53.30	$53.30	$53.30
Purchase #5	$177.41	5.546%	$187.2492	$187.25	$187.25	$187.20
Purchase #6	$196.67	8.252%	$212.8992	$212.90	$212.90	$212.90
Purchase #7	$19.44	5.874%	$20.5819	$20.58	$20.60	$20.60
7 purchase totals =	$722.29		$768.6122	$768.61	$768.60	$768.50