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	$97.99	13.723%	$111.4372	$111.44	$111.45	$111.40
Purchase #2	$242.89	4.151%	$252.9724	$252.97	$252.95	$253.00
Purchase #3	$85.93	5.217%	$90.413	$90.41	$90.40	$90.40
Purchase #4	$40.94	13.678%	$46.5398	$46.54	$46.55	$46.50
Purchase #5	$162.80	11.482%	$181.4927	$181.49	$181.50	$181.50
Purchase #6	$245.33	5.187%	$258.0553	$258.06	$258.05	$258.10
Purchase #7	$56.55	5.136%	$59.4544	$59.45	$59.45	$59.50
7 purchase totals =	$932.43		$1,000.3648	$1,000.36	$1,000.35	$1,000.40