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	$241.88	10.407%	$267.0525	$267.05	$267.05	$267.10
Purchase #2	$41.44	3.307%	$42.8104	$42.81	$42.80	$42.80
Purchase #3	$147.65	13.433%	$167.4838	$167.48	$167.50	$167.50
Purchase #4	$133.28	5.826%	$141.0449	$141.04	$141.05	$141.00
Purchase #5	$204.56	10.858%	$226.7711	$226.77	$226.75	$226.80
Purchase #6	$171.66	5.362%	$180.8644	$180.86	$180.85	$180.90
Purchase #7	$161.98	5.238%	$170.4645	$170.46	$170.45	$170.50
7 purchase totals =	$1,102.45		$1,196.4916	$1,196.47	$1,196.45	$1,196.60