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	$208.26	4.240%	$217.0902	$217.09	$217.10	$217.10
Purchase #2	$172.92	9.621%	$189.5566	$189.56	$189.55	$189.60
Purchase #3	$189.31	6.160%	$200.9715	$200.97	$200.95	$201.00
Purchase #4	$127.65	10.488%	$141.0379	$141.04	$141.05	$141.00
Purchase #5	$72.59	5.501%	$76.5832	$76.58	$76.60	$76.60
Purchase #6	$150.30	6.192%	$159.6066	$159.61	$159.60	$159.60
Purchase #7	$126.57	11.825%	$141.5369	$141.54	$141.55	$141.50
7 purchase totals =	$1,047.60		$1,126.3829	$1,126.39	$1,126.40	$1,126.40