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	$158.54	11.616%	$176.956	$176.96	$176.95	$177.00
Purchase #2	$184.62	5.361%	$194.5175	$194.52	$194.50	$194.50
Purchase #3	$27.77	3.403%	$28.715	$28.72	$28.70	$28.70
Purchase #4	$242.33	7.697%	$260.9821	$260.98	$261.00	$261.00
Purchase #5	$82.54	4.221%	$86.024	$86.02	$86.00	$86.00
Purchase #6	$54.26	9.519%	$59.425	$59.43	$59.45	$59.40
Purchase #7	$179.75	11.598%	$200.5974	$200.60	$200.60	$200.60
7 purchase totals =	$929.81		$1,007.2170	$1,007.23	$1,007.20	$1,007.20