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	$43.70	5.579%	$46.138	$46.14	$46.15	$46.10
Purchase #2	$69.97	3.731%	$72.5806	$72.58	$72.60	$72.60
Purchase #3	$27.54	9.497%	$30.1555	$30.16	$30.15	$30.20
Purchase #4	$39.26	11.695%	$43.8515	$43.85	$43.85	$43.90
Purchase #5	$50.95	6.729%	$54.3784	$54.38	$54.40	$54.40
Purchase #6	$235.87	8.616%	$256.1926	$256.19	$256.20	$256.20
Purchase #7	$208.96	9.539%	$228.8927	$228.89	$228.90	$228.90
7 purchase totals =	$676.25		$732.1893	$732.19	$732.25	$732.30