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	$179.82	9.207%	$196.376	$196.38	$196.40	$196.40
Purchase #2	$150.27	9.765%	$164.9439	$164.94	$164.95	$164.90
Purchase #3	$68.48	9.172%	$74.761	$74.76	$74.75	$74.80
Purchase #4	$50.86	9.298%	$55.589	$55.59	$55.60	$55.60
Purchase #5	$157.49	3.847%	$163.5486	$163.55	$163.55	$163.50
Purchase #6	$194.77	7.384%	$209.1518	$209.15	$209.15	$209.20
Purchase #7	$139.49	9.252%	$152.3956	$152.40	$152.40	$152.40
7 purchase totals =	$941.18		$1,016.7659	$1,016.77	$1,016.80	$1,016.80