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	$58.83	4.820%	$61.6656	$61.67	$61.65	$61.70
Purchase #2	$66.42	8.644%	$72.1613	$72.16	$72.15	$72.20
Purchase #3	$138.27	3.809%	$143.5367	$143.54	$143.55	$143.50
Purchase #4	$71.79	4.321%	$74.892	$74.89	$74.90	$74.90
Purchase #5	$246.59	8.708%	$268.0631	$268.06	$268.05	$268.10
Purchase #6	$195.99	8.632%	$212.9079	$212.91	$212.90	$212.90
Purchase #7	$224.59	8.781%	$244.3112	$244.31	$244.30	$244.30
7 purchase totals =	$1,002.48		$1,077.5378	$1,077.54	$1,077.50	$1,077.60