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	$105.80	11.839%	$118.3257	$118.33	$118.35	$118.30
Purchase #2	$154.50	11.145%	$171.719	$171.72	$171.70	$171.70
Purchase #3	$39.97	13.549%	$45.3855	$45.39	$45.40	$45.40
Purchase #4	$67.47	7.153%	$72.2961	$72.30	$72.30	$72.30
Purchase #5	$187.38	12.365%	$210.5495	$210.55	$210.55	$210.50
Purchase #6	$214.26	7.614%	$230.5738	$230.57	$230.55	$230.60
Purchase #7	$165.98	4.811%	$173.9653	$173.97	$173.95	$174.00
7 purchase totals =	$935.36		$1,022.8149	$1,022.83	$1,022.80	$1,022.80