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	$186.95	11.299%	$208.0735	$208.07	$208.05	$208.10
Purchase #2	$238.69	3.467%	$246.9654	$246.97	$246.95	$247.00
Purchase #3	$175.63	9.295%	$191.9548	$191.95	$191.95	$192.00
Purchase #4	$103.57	5.408%	$109.1711	$109.17	$109.15	$109.20
Purchase #5	$139.69	9.234%	$152.589	$152.59	$152.60	$152.60
Purchase #6	$60.63	9.646%	$66.4784	$66.48	$66.50	$66.50
Purchase #7	$81.48	6.281%	$86.5978	$86.60	$86.60	$86.60
7 purchase totals =	$986.64		$1,061.8300	$1,061.83	$1,061.80	$1,062.00