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	$80.55	6.721%	$85.9638	$85.96	$85.95	$86.00
Purchase #2	$98.31	13.239%	$111.3253	$111.33	$111.35	$111.30
Purchase #3	$182.70	7.592%	$196.5706	$196.57	$196.55	$196.60
Purchase #4	$35.36	11.588%	$39.4575	$39.46	$39.45	$39.50
Purchase #5	$104.91	8.424%	$113.7476	$113.75	$113.75	$113.70
Purchase #6	$87.34	8.273%	$94.5656	$94.57	$94.55	$94.60
Purchase #7	$63.49	3.308%	$65.5902	$65.59	$65.60	$65.60
7 purchase totals =	$652.66		$707.2206	$707.23	$707.20	$707.30