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	$162.66	8.244%	$176.0697	$176.07	$176.05	$176.10
Purchase #2	$155.82	8.321%	$168.7858	$168.79	$168.80	$168.80
Purchase #3	$75.35	9.152%	$82.246	$82.25	$82.25	$82.20
Purchase #4	$145.32	9.196%	$158.6836	$158.68	$158.70	$158.70
Purchase #5	$55.86	10.661%	$61.8152	$61.82	$61.80	$61.80
Purchase #6	$173.88	10.399%	$191.9618	$191.96	$191.95	$192.00
Purchase #7	$229.84	7.283%	$246.5792	$246.58	$246.60	$246.60
7 purchase totals =	$998.73		$1,086.1413	$1,086.15	$1,086.15	$1,086.20