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	$175.90	9.622%	$192.8251	$192.83	$192.85	$192.80
Purchase #2	$191.48	11.525%	$213.5481	$213.55	$213.55	$213.50
Purchase #3	$87.47	3.149%	$90.2244	$90.22	$90.20	$90.20
Purchase #4	$160.62	11.505%	$179.0993	$179.10	$179.10	$179.10
Purchase #5	$196.81	9.686%	$215.873	$215.87	$215.85	$215.90
Purchase #6	$57.80	13.211%	$65.436	$65.44	$65.45	$65.40
Purchase #7	$141.57	4.273%	$147.6193	$147.62	$147.60	$147.60
7 purchase totals =	$1,011.65		$1,104.6252	$1,104.63	$1,104.60	$1,104.50