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	$196.59	10.234%	$216.709	$216.71	$216.70	$216.70
Purchase #2	$19.66	3.235%	$20.296	$20.30	$20.30	$20.30
Purchase #3	$223.97	7.525%	$240.8237	$240.82	$240.80	$240.80
Purchase #4	$207.70	12.325%	$233.299	$233.30	$233.30	$233.30
Purchase #5	$148.55	13.102%	$168.013	$168.01	$168.00	$168.00
Purchase #6	$90.62	5.426%	$95.537	$95.54	$95.55	$95.50
Purchase #7	$247.68	10.469%	$273.6096	$273.61	$273.60	$273.60
7 purchase totals =	$1,134.77		$1,248.2873	$1,248.29	$1,248.25	$1,248.20