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	$164.93	4.183%	$171.829	$171.83	$171.85	$171.80
Purchase #2	$193.35	12.583%	$217.6792	$217.68	$217.70	$217.70
Purchase #3	$31.45	13.154%	$35.5869	$35.59	$35.60	$35.60
Purchase #4	$195.51	6.549%	$208.3139	$208.31	$208.30	$208.30
Purchase #5	$141.98	10.639%	$157.0853	$157.09	$157.10	$157.10
Purchase #6	$123.88	13.390%	$140.4675	$140.47	$140.45	$140.50
Purchase #7	$78.34	10.502%	$86.5673	$86.57	$86.55	$86.60
7 purchase totals =	$929.44		$1,017.5291	$1,017.54	$1,017.55	$1,017.60