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	$199.29	8.192%	$215.6158	$215.62	$215.60	$215.60
Purchase #2	$17.77	5.791%	$18.7991	$18.80	$18.80	$18.80
Purchase #3	$236.86	4.838%	$248.3193	$248.32	$248.30	$248.30
Purchase #4	$56.51	9.502%	$61.8796	$61.88	$61.90	$61.90
Purchase #5	$188.33	5.589%	$198.8558	$198.86	$198.85	$198.90
Purchase #6	$173.83	10.178%	$191.5224	$191.52	$191.50	$191.50
Purchase #7	$167.96	4.848%	$176.1027	$176.10	$176.10	$176.10
7 purchase totals =	$1,040.55		$1,111.0947	$1,111.10	$1,111.05	$1,111.10