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	$176.50	11.511%	$196.8169	$196.82	$196.80	$196.80
Purchase #2	$83.96	10.831%	$93.0537	$93.05	$93.05	$93.10
Purchase #3	$29.62	13.233%	$33.5396	$33.54	$33.55	$33.50
Purchase #4	$102.83	8.415%	$111.4831	$111.48	$111.50	$111.50
Purchase #5	$181.65	3.856%	$188.6544	$188.65	$188.65	$188.70
Purchase #6	$181.46	8.141%	$196.2327	$196.23	$196.25	$196.20
Purchase #7	$174.99	3.470%	$181.0622	$181.06	$181.05	$181.10
7 purchase totals =	$931.01		$1,000.8426	$1,000.83	$1,000.85	$1,000.90