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	$217.43	5.143%	$228.6124	$228.61	$228.60	$228.60
Purchase #2	$206.97	10.838%	$229.4014	$229.40	$229.40	$229.40
Purchase #3	$80.80	6.612%	$86.1425	$86.14	$86.15	$86.10
Purchase #4	$201.95	10.373%	$222.8983	$222.90	$222.90	$222.90
Purchase #5	$233.75	7.351%	$250.933	$250.93	$250.95	$250.90
Purchase #6	$52.31	13.354%	$59.2955	$59.30	$59.30	$59.30
Purchase #7	$64.52	6.195%	$68.517	$68.52	$68.50	$68.50
7 purchase totals =	$1,057.73		$1,145.8001	$1,145.80	$1,145.80	$1,145.70