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	$228.38	3.156%	$235.5877	$235.59	$235.60	$235.60
Purchase #2	$77.56	10.234%	$85.4975	$85.50	$85.50	$85.50
Purchase #3	$62.74	7.232%	$67.2774	$67.28	$67.30	$67.30
Purchase #4	$138.96	8.483%	$150.748	$150.75	$150.75	$150.70
Purchase #5	$208.35	13.578%	$236.6398	$236.64	$236.65	$236.60
Purchase #6	$141.26	6.582%	$150.5577	$150.56	$150.55	$150.60
Purchase #7	$225.42	9.268%	$246.3119	$246.31	$246.30	$246.30
7 purchase totals =	$1,082.67		$1,172.6200	$1,172.63	$1,172.65	$1,172.60