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	$114.95	7.342%	$123.3896	$123.39	$123.40	$123.40
Purchase #2	$26.46	7.774%	$28.517	$28.52	$28.50	$28.50
Purchase #3	$175.50	11.710%	$196.0511	$196.05	$196.05	$196.10
Purchase #4	$49.90	10.516%	$55.1475	$55.15	$55.15	$55.10
Purchase #5	$105.90	3.833%	$109.9591	$109.96	$109.95	$110.00
Purchase #6	$47.96	5.382%	$50.5412	$50.54	$50.55	$50.50
Purchase #7	$190.67	4.583%	$199.4084	$199.41	$199.40	$199.40
7 purchase totals =	$711.34		$763.0139	$763.02	$763.00	$763.00