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	$22.66	11.144%	$25.1852	$25.19	$25.20	$25.20
Purchase #2	$169.59	4.791%	$177.7151	$177.72	$177.70	$177.70
Purchase #3	$182.69	7.448%	$196.2968	$196.30	$196.30	$196.30
Purchase #4	$207.53	7.419%	$222.9267	$222.93	$222.95	$222.90
Purchase #5	$199.78	4.274%	$208.3186	$208.32	$208.30	$208.30
Purchase #6	$209.64	5.616%	$221.4134	$221.41	$221.40	$221.40
Purchase #7	$101.29	11.144%	$112.5778	$112.58	$112.60	$112.60
7 purchase totals =	$1,093.18		$1,164.4336	$1,164.45	$1,164.45	$1,164.40