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	$112.71	7.314%	$120.9536	$120.95	$120.95	$121.00
Purchase #2	$184.77	3.624%	$191.4661	$191.47	$191.45	$191.50
Purchase #3	$187.59	6.630%	$200.0272	$200.03	$200.05	$200.00
Purchase #4	$116.47	4.827%	$122.092	$122.09	$122.10	$122.10
Purchase #5	$108.33	3.505%	$112.127	$112.13	$112.15	$112.10
Purchase #6	$183.38	7.114%	$196.4257	$196.43	$196.45	$196.40
Purchase #7	$112.54	5.772%	$119.0358	$119.04	$119.05	$119.00
7 purchase totals =	$1,005.79		$1,062.1274	$1,062.14	$1,062.20	$1,062.10