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	$164.85	10.410%	$182.0109	$182.01	$182.00	$182.00
Purchase #2	$194.72	9.630%	$213.4715	$213.47	$213.45	$213.50
Purchase #3	$61.33	5.744%	$64.8528	$64.85	$64.85	$64.90
Purchase #4	$117.72	12.408%	$132.3267	$132.33	$132.35	$132.30
Purchase #5	$7.32	7.695%	$7.8833	$7.88	$7.90	$7.90
Purchase #6	$90.49	8.153%	$97.8676	$97.87	$97.85	$97.90
Purchase #7	$176.95	8.456%	$191.9129	$191.91	$191.90	$191.90
7 purchase totals =	$813.38		$890.3257	$890.32	$890.30	$890.40