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	$248.29	13.358%	$281.4566	$281.46	$281.45	$281.50
Purchase #2	$210.41	3.287%	$217.3262	$217.33	$217.35	$217.30
Purchase #3	$209.78	10.465%	$231.7335	$231.73	$231.75	$231.70
Purchase #4	$38.46	13.745%	$43.7463	$43.75	$43.75	$43.70
Purchase #5	$150.54	10.623%	$166.5319	$166.53	$166.55	$166.50
Purchase #6	$119.75	12.638%	$134.884	$134.88	$134.90	$134.90
Purchase #7	$110.36	9.314%	$120.6389	$120.64	$120.65	$120.60
7 purchase totals =	$1,087.59		$1,196.3174	$1,196.32	$1,196.40	$1,196.20