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	$142.38	10.149%	$156.8301	$156.83	$156.85	$156.80
Purchase #2	$145.50	5.542%	$153.5636	$153.56	$153.55	$153.60
Purchase #3	$82.56	9.826%	$90.6723	$90.67	$90.65	$90.70
Purchase #4	$246.27	4.870%	$258.2633	$258.26	$258.25	$258.30
Purchase #5	$219.29	5.257%	$230.8181	$230.82	$230.80	$230.80
Purchase #6	$110.96	6.788%	$118.492	$118.49	$118.50	$118.50
Purchase #7	$186.59	5.218%	$196.3263	$196.33	$196.35	$196.30
7 purchase totals =	$1,133.55		$1,204.9657	$1,204.96	$1,204.95	$1,205.00