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	$156.56	8.360%	$169.6484	$169.65	$169.65	$169.60
Purchase #2	$14.68	4.173%	$15.2926	$15.29	$15.30	$15.30
Purchase #3	$111.98	11.813%	$125.2082	$125.21	$125.20	$125.20
Purchase #4	$164.45	4.416%	$171.7121	$171.71	$171.70	$171.70
Purchase #5	$199.43	11.837%	$223.0365	$223.04	$223.05	$223.00
Purchase #6	$151.80	9.153%	$165.6943	$165.69	$165.70	$165.70
Purchase #7	$103.86	7.672%	$111.8281	$111.83	$111.85	$111.80
7 purchase totals =	$902.76		$982.4202	$982.42	$982.45	$982.30