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	$21.87	9.522%	$23.9525	$23.95	$23.95	$24.00
Purchase #2	$211.31	5.111%	$222.1101	$222.11	$222.10	$222.10
Purchase #3	$42.82	5.379%	$45.1233	$45.12	$45.10	$45.10
Purchase #4	$117.54	13.130%	$132.973	$132.97	$132.95	$133.00
Purchase #5	$41.56	8.446%	$45.0702	$45.07	$45.05	$45.10
Purchase #6	$199.61	4.111%	$207.816	$207.82	$207.80	$207.80
Purchase #7	$67.41	7.370%	$72.3781	$72.38	$72.40	$72.40
7 purchase totals =	$702.12		$749.4232	$749.42	$749.35	$749.50