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	$158.47	3.783%	$164.4649	$164.46	$164.45	$164.50
Purchase #2	$208.63	6.713%	$222.6353	$222.64	$222.65	$222.60
Purchase #3	$122.57	5.559%	$129.3837	$129.38	$129.40	$129.40
Purchase #4	$98.56	6.696%	$105.1596	$105.16	$105.15	$105.20
Purchase #5	$113.91	5.623%	$120.3152	$120.32	$120.30	$120.30
Purchase #6	$118.78	13.141%	$134.3889	$134.39	$134.40	$134.40
Purchase #7	$226.52	4.259%	$236.1675	$236.17	$236.15	$236.20
7 purchase totals =	$1,047.44		$1,112.5151	$1,112.52	$1,112.50	$1,112.60