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	$56.48	10.547%	$62.4369	$62.44	$62.45	$62.40
Purchase #2	$107.85	4.692%	$112.9103	$112.91	$112.90	$112.90
Purchase #3	$185.71	3.561%	$192.3231	$192.32	$192.30	$192.30
Purchase #4	$35.66	4.740%	$37.3503	$37.35	$37.35	$37.40
Purchase #5	$25.65	12.833%	$28.9417	$28.94	$28.95	$28.90
Purchase #6	$58.54	13.480%	$66.4312	$66.43	$66.45	$66.40
Purchase #7	$199.87	12.318%	$224.49	$224.49	$224.50	$224.50
7 purchase totals =	$669.76		$724.8835	$724.88	$724.90	$724.80