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	$215.54	7.352%	$231.3865	$231.39	$231.40	$231.40
Purchase #2	$158.86	7.344%	$170.5267	$170.53	$170.55	$170.50
Purchase #3	$87.27	7.549%	$93.858	$93.86	$93.85	$93.90
Purchase #4	$210.59	11.524%	$234.8584	$234.86	$234.85	$234.90
Purchase #5	$141.53	5.713%	$149.6156	$149.62	$149.60	$149.60
Purchase #6	$131.47	11.670%	$146.8125	$146.81	$146.80	$146.80
Purchase #7	$72.62	7.761%	$78.256	$78.26	$78.25	$78.30
7 purchase totals =	$1,017.88		$1,105.3137	$1,105.33	$1,105.30	$1,105.40