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	$248.96	5.462%	$262.5582	$262.56	$262.55	$262.60
Purchase #2	$175.73	6.623%	$187.3686	$187.37	$187.35	$187.40
Purchase #3	$109.31	13.804%	$124.3992	$124.40	$124.40	$124.40
Purchase #4	$234.55	3.305%	$242.3019	$242.30	$242.30	$242.30
Purchase #5	$68.85	4.172%	$71.7224	$71.72	$71.70	$71.70
Purchase #6	$121.78	9.664%	$133.5488	$133.55	$133.55	$133.50
Purchase #7	$85.39	4.476%	$89.2121	$89.21	$89.20	$89.20
7 purchase totals =	$1,044.57		$1,111.1112	$1,111.11	$1,111.05	$1,111.10