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	$58.58	6.374%	$62.3139	$62.31	$62.30	$62.30
Purchase #2	$153.34	6.479%	$163.2749	$163.27	$163.25	$163.30
Purchase #3	$187.76	4.774%	$196.7237	$196.72	$196.70	$196.70
Purchase #4	$13.93	11.131%	$15.4805	$15.48	$15.50	$15.50
Purchase #5	$49.45	4.753%	$51.8004	$51.80	$51.80	$51.80
Purchase #6	$32.73	13.112%	$37.0216	$37.02	$37.00	$37.00
Purchase #7	$155.96	11.535%	$173.95	$173.95	$173.95	$174.00
7 purchase totals =	$651.75		$700.5650	$700.55	$700.50	$700.60