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	$105.41	5.639%	$111.3541	$111.35	$111.35	$111.40
Purchase #2	$45.27	4.252%	$47.1949	$47.19	$47.20	$47.20
Purchase #3	$215.45	10.761%	$238.6346	$238.63	$238.65	$238.60
Purchase #4	$245.58	10.714%	$271.8914	$271.89	$271.90	$271.90
Purchase #5	$64.25	5.229%	$67.6096	$67.61	$67.60	$67.60
Purchase #6	$221.30	9.265%	$241.8034	$241.80	$241.80	$241.80
Purchase #7	$205.94	5.280%	$216.8136	$216.81	$216.80	$216.80
7 purchase totals =	$1,103.20		$1,195.3016	$1,195.28	$1,195.30	$1,195.30