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	$244.41	7.355%	$262.3864	$262.39	$262.40	$262.40
Purchase #2	$51.76	5.122%	$54.4111	$54.41	$54.40	$54.40
Purchase #3	$29.42	13.287%	$33.329	$33.33	$33.35	$33.30
Purchase #4	$106.81	3.343%	$110.3807	$110.38	$110.40	$110.40
Purchase #5	$46.76	5.760%	$49.4534	$49.45	$49.45	$49.50
Purchase #6	$89.50	7.873%	$96.5463	$96.55	$96.55	$96.50
Purchase #7	$112.98	3.428%	$116.853	$116.85	$116.85	$116.90
7 purchase totals =	$681.64		$723.3599	$723.36	$723.40	$723.40