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	$173.32	3.593%	$179.5474	$179.55	$179.55	$179.50
Purchase #2	$31.81	6.164%	$33.7708	$33.77	$33.75	$33.80
Purchase #3	$80.51	6.464%	$85.7142	$85.71	$85.70	$85.70
Purchase #4	$172.55	10.486%	$190.6436	$190.64	$190.65	$190.60
Purchase #5	$196.75	7.618%	$211.7384	$211.74	$211.75	$211.70
Purchase #6	$144.71	13.525%	$164.282	$164.28	$164.30	$164.30
Purchase #7	$180.33	6.786%	$192.5672	$192.57	$192.55	$192.60
7 purchase totals =	$979.98		$1,058.2636	$1,058.26	$1,058.25	$1,058.20