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	$175.85	10.681%	$194.6325	$194.63	$194.65	$194.60
Purchase #2	$230.62	3.413%	$238.4911	$238.49	$238.50	$238.50
Purchase #3	$131.37	10.337%	$144.9497	$144.95	$144.95	$144.90
Purchase #4	$137.50	13.554%	$156.1368	$156.14	$156.15	$156.10
Purchase #5	$208.34	3.371%	$215.3631	$215.36	$215.35	$215.40
Purchase #6	$32.90	13.344%	$37.2902	$37.29	$37.30	$37.30
Purchase #7	$39.58	12.486%	$44.522	$44.52	$44.50	$44.50
7 purchase totals =	$956.16		$1,031.3854	$1,031.38	$1,031.40	$1,031.30