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	$209.78	11.263%	$233.4075	$233.41	$233.40	$233.40
Purchase #2	$190.73	10.802%	$211.3327	$211.33	$211.35	$211.30
Purchase #3	$128.42	11.175%	$142.7709	$142.77	$142.75	$142.80
Purchase #4	$182.89	8.652%	$198.7136	$198.71	$198.70	$198.70
Purchase #5	$124.35	7.177%	$133.2746	$133.27	$133.25	$133.30
Purchase #6	$56.70	5.321%	$59.717	$59.72	$59.70	$59.70
Purchase #7	$95.77	7.171%	$102.6377	$102.64	$102.65	$102.60
7 purchase totals =	$988.64		$1,081.8540	$1,081.85	$1,081.80	$1,081.80