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	$208.41	9.280%	$227.7504	$227.75	$227.75	$227.80
Purchase #2	$223.91	13.790%	$254.7872	$254.79	$254.80	$254.80
Purchase #3	$160.55	4.417%	$167.6415	$167.64	$167.65	$167.60
Purchase #4	$215.27	4.736%	$225.4652	$225.47	$225.45	$225.50
Purchase #5	$86.46	10.752%	$95.7562	$95.76	$95.75	$95.80
Purchase #6	$228.86	5.446%	$241.3237	$241.32	$241.30	$241.30
Purchase #7	$33.86	10.408%	$37.3841	$37.38	$37.40	$37.40
7 purchase totals =	$1,157.32		$1,250.1083	$1,250.11	$1,250.10	$1,250.20