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	$95.46	3.662%	$98.9557	$98.96	$98.95	$99.00
Purchase #2	$134.94	13.516%	$153.1785	$153.18	$153.20	$153.20
Purchase #3	$169.51	5.747%	$179.2517	$179.25	$179.25	$179.30
Purchase #4	$238.63	6.625%	$254.4392	$254.44	$254.45	$254.40
Purchase #5	$203.45	13.710%	$231.343	$231.34	$231.35	$231.30
Purchase #6	$10.27	12.770%	$11.5815	$11.58	$11.60	$11.60
Purchase #7	$136.78	11.674%	$152.7477	$152.75	$152.75	$152.70
7 purchase totals =	$989.04		$1,081.4973	$1,081.50	$1,081.55	$1,081.50