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	$54.54	9.345%	$59.6368	$59.64	$59.65	$59.60
Purchase #2	$201.38	6.197%	$213.8595	$213.86	$213.85	$213.90
Purchase #3	$41.47	5.597%	$43.7911	$43.79	$43.80	$43.80
Purchase #4	$171.44	9.350%	$187.4696	$187.47	$187.45	$187.50
Purchase #5	$249.26	10.387%	$275.1506	$275.15	$275.15	$275.20
Purchase #6	$242.41	11.270%	$269.7296	$269.73	$269.75	$269.70
Purchase #7	$16.45	6.571%	$17.5309	$17.53	$17.55	$17.50
7 purchase totals =	$976.95		$1,067.1681	$1,067.17	$1,067.20	$1,067.20