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	$126.89	3.273%	$131.0431	$131.04	$131.05	$131.00
Purchase #2	$66.36	7.488%	$71.329	$71.33	$71.35	$71.30
Purchase #3	$239.57	6.583%	$255.3409	$255.34	$255.35	$255.30
Purchase #4	$171.56	12.256%	$192.5864	$192.59	$192.60	$192.60
Purchase #5	$193.36	3.792%	$200.6922	$200.69	$200.70	$200.70
Purchase #6	$71.77	7.242%	$76.9676	$76.97	$76.95	$77.00
Purchase #7	$173.71	12.501%	$195.4255	$195.43	$195.45	$195.40
7 purchase totals =	$1,043.22		$1,123.3847	$1,123.39	$1,123.45	$1,123.30