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	$78.92	9.558%	$86.4632	$86.46	$86.45	$86.50
Purchase #2	$205.51	5.448%	$216.7062	$216.71	$216.70	$216.70
Purchase #3	$70.37	3.524%	$72.8498	$72.85	$72.85	$72.80
Purchase #4	$127.97	9.263%	$139.8239	$139.82	$139.80	$139.80
Purchase #5	$189.75	11.779%	$212.1007	$212.10	$212.10	$212.10
Purchase #6	$130.85	7.488%	$140.648	$140.65	$140.65	$140.60
Purchase #7	$200.31	13.466%	$227.2837	$227.28	$227.30	$227.30
7 purchase totals =	$1,003.68		$1,095.8755	$1,095.87	$1,095.85	$1,095.80