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	$168.83	12.448%	$189.846	$189.85	$189.85	$189.80
Purchase #2	$210.66	13.754%	$239.6342	$239.63	$239.65	$239.60
Purchase #3	$223.68	11.269%	$248.8865	$248.89	$248.90	$248.90
Purchase #4	$94.87	4.719%	$99.3469	$99.35	$99.35	$99.30
Purchase #5	$200.99	5.267%	$211.5761	$211.58	$211.60	$211.60
Purchase #6	$227.95	11.673%	$254.5586	$254.56	$254.55	$254.60
Purchase #7	$190.93	4.587%	$199.688	$199.69	$199.70	$199.70
7 purchase totals =	$1,317.91		$1,443.5363	$1,443.55	$1,443.60	$1,443.50