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	$43.40	10.752%	$48.0664	$48.07	$48.05	$48.10
Purchase #2	$222.67	7.580%	$239.5484	$239.55	$239.55	$239.50
Purchase #3	$90.69	13.623%	$103.0447	$103.04	$103.05	$103.00
Purchase #4	$37.52	11.807%	$41.95	$41.95	$41.95	$42.00
Purchase #5	$63.63	12.323%	$71.4711	$71.47	$71.45	$71.50
Purchase #6	$216.84	3.645%	$224.7438	$224.74	$224.75	$224.70
Purchase #7	$66.94	8.504%	$72.6326	$72.63	$72.65	$72.60
7 purchase totals =	$741.69		$801.4570	$801.45	$801.45	$801.40