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	$69.52	9.423%	$76.0709	$76.07	$76.05	$76.10
Purchase #2	$24.36	13.677%	$27.6917	$27.69	$27.70	$27.70
Purchase #3	$230.80	7.697%	$248.5647	$248.56	$248.55	$248.60
Purchase #4	$189.86	3.458%	$196.4254	$196.43	$196.45	$196.40
Purchase #5	$246.50	3.654%	$255.5071	$255.51	$255.50	$255.50
Purchase #6	$76.57	12.694%	$86.2898	$86.29	$86.30	$86.30
Purchase #7	$37.26	11.623%	$41.5907	$41.59	$41.60	$41.60
7 purchase totals =	$874.87		$932.1403	$932.14	$932.15	$932.20