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	$84.58	10.254%	$93.2528	$93.25	$93.25	$93.30
Purchase #2	$167.98	12.259%	$188.5727	$188.57	$188.55	$188.60
Purchase #3	$175.43	12.203%	$196.8377	$196.84	$196.85	$196.80
Purchase #4	$208.90	10.861%	$231.5886	$231.59	$231.60	$231.60
Purchase #5	$126.29	12.157%	$141.6431	$141.64	$141.65	$141.60
Purchase #6	$94.50	6.119%	$100.2825	$100.28	$100.30	$100.30
Purchase #7	$92.78	11.698%	$103.6334	$103.63	$103.65	$103.60
7 purchase totals =	$950.46		$1,055.8108	$1,055.80	$1,055.85	$1,055.80