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	$146.55	10.603%	$162.0887	$162.09	$162.10	$162.10
Purchase #2	$6.41	13.102%	$7.2498	$7.25	$7.25	$7.20
Purchase #3	$85.78	12.402%	$96.4184	$96.42	$96.40	$96.40
Purchase #4	$234.77	8.812%	$255.4579	$255.46	$255.45	$255.50
Purchase #5	$154.44	6.711%	$164.8045	$164.80	$164.80	$164.80
Purchase #6	$176.75	12.654%	$199.1159	$199.12	$199.10	$199.10
Purchase #7	$155.99	13.262%	$176.6774	$176.68	$176.70	$176.70
7 purchase totals =	$960.69		$1,061.8126	$1,061.82	$1,061.80	$1,061.80