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	$146.34	11.292%	$162.8647	$162.86	$162.85	$162.90
Purchase #2	$186.79	13.170%	$211.3902	$211.39	$211.40	$211.40
Purchase #3	$140.60	13.543%	$159.6415	$159.64	$159.65	$159.60
Purchase #4	$39.31	3.683%	$40.7578	$40.76	$40.75	$40.80
Purchase #5	$64.66	11.536%	$72.1192	$72.12	$72.10	$72.10
Purchase #6	$169.80	6.563%	$180.944	$180.94	$180.95	$180.90
Purchase #7	$188.78	10.470%	$208.5453	$208.55	$208.55	$208.50
7 purchase totals =	$936.28		$1,036.2627	$1,036.26	$1,036.25	$1,036.20