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	$211.90	6.311%	$225.273	$225.27	$225.25	$225.30
Purchase #2	$38.65	11.856%	$43.2323	$43.23	$43.25	$43.20
Purchase #3	$36.32	8.858%	$39.5372	$39.54	$39.55	$39.50
Purchase #4	$127.77	4.275%	$133.2322	$133.23	$133.25	$133.20
Purchase #5	$48.31	8.109%	$52.2275	$52.23	$52.25	$52.20
Purchase #6	$171.66	4.286%	$179.0173	$179.02	$179.00	$179.00
Purchase #7	$49.57	6.485%	$52.7846	$52.78	$52.80	$52.80
7 purchase totals =	$684.18		$725.3041	$725.30	$725.35	$725.20