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	$201.65	4.310%	$210.3411	$210.34	$210.35	$210.30
Purchase #2	$204.52	4.817%	$214.3717	$214.37	$214.35	$214.40
Purchase #3	$160.78	3.181%	$165.8944	$165.89	$165.90	$165.90
Purchase #4	$82.75	3.387%	$85.5527	$85.55	$85.55	$85.60
Purchase #5	$245.44	5.279%	$258.3968	$258.40	$258.40	$258.40
Purchase #6	$212.90	12.213%	$238.9015	$238.90	$238.90	$238.90
Purchase #7	$187.86	5.527%	$198.243	$198.24	$198.25	$198.20
7 purchase totals =	$1,295.90		$1,371.7012	$1,371.69	$1,371.70	$1,371.70