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	$54.86	13.559%	$62.2985	$62.30	$62.30	$62.30
Purchase #2	$18.96	13.596%	$21.5378	$21.54	$21.55	$21.50
Purchase #3	$186.85	4.485%	$195.2302	$195.23	$195.25	$195.20
Purchase #4	$120.63	11.171%	$134.1056	$134.11	$134.10	$134.10
Purchase #5	$167.92	13.154%	$190.0082	$190.01	$190.00	$190.00
Purchase #6	$179.59	11.561%	$200.3524	$200.35	$200.35	$200.40
Purchase #7	$27.37	5.791%	$28.955	$28.96	$28.95	$29.00
7 purchase totals =	$756.18		$832.4877	$832.50	$832.50	$832.50