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	$67.25	13.613%	$76.4047	$76.40	$76.40	$76.40
Purchase #2	$91.91	5.513%	$96.977	$96.98	$97.00	$97.00
Purchase #3	$49.41	4.873%	$51.8177	$51.82	$51.80	$51.80
Purchase #4	$190.75	3.177%	$196.8101	$196.81	$196.80	$196.80
Purchase #5	$172.57	12.307%	$193.8082	$193.81	$193.80	$193.80
Purchase #6	$130.68	9.352%	$142.9012	$142.90	$142.90	$142.90
Purchase #7	$59.67	12.816%	$67.3173	$67.32	$67.30	$67.30
7 purchase totals =	$762.24		$826.0362	$826.04	$826.00	$826.00