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	$152.38	11.471%	$169.8595	$169.86	$169.85	$169.90
Purchase #2	$116.45	11.403%	$129.7288	$129.73	$129.75	$129.70
Purchase #3	$139.57	5.704%	$147.5311	$147.53	$147.55	$147.50
Purchase #4	$35.99	6.799%	$38.437	$38.44	$38.45	$38.40
Purchase #5	$214.95	3.540%	$222.5592	$222.56	$222.55	$222.60
Purchase #6	$168.92	8.108%	$182.616	$182.62	$182.60	$182.60
Purchase #7	$158.98	7.310%	$170.6014	$170.60	$170.60	$170.60
7 purchase totals =	$987.24		$1,061.3330	$1,061.34	$1,061.35	$1,061.30