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	$173.33	11.142%	$192.6424	$192.64	$192.65	$192.60
Purchase #2	$80.95	13.107%	$91.5601	$91.56	$91.55	$91.60
Purchase #3	$182.59	9.232%	$199.4467	$199.45	$199.45	$199.40
Purchase #4	$186.71	3.127%	$192.5484	$192.55	$192.55	$192.50
Purchase #5	$184.44	13.701%	$209.7101	$209.71	$209.70	$209.70
Purchase #6	$55.79	6.838%	$59.6049	$59.60	$59.60	$59.60
Purchase #7	$108.86	10.231%	$119.9975	$120.00	$120.00	$120.00
7 purchase totals =	$972.67		$1,065.5101	$1,065.51	$1,065.50	$1,065.40