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	$35.80	8.515%	$38.8484	$38.85	$38.85	$38.80
Purchase #2	$48.42	10.855%	$53.676	$53.68	$53.70	$53.70
Purchase #3	$46.50	13.673%	$52.8579	$52.86	$52.85	$52.90
Purchase #4	$46.83	5.594%	$49.4497	$49.45	$49.45	$49.40
Purchase #5	$28.81	4.507%	$30.1085	$30.11	$30.10	$30.10
Purchase #6	$64.86	12.442%	$72.9299	$72.93	$72.95	$72.90
Purchase #7	$150.38	12.706%	$169.4873	$169.49	$169.50	$169.50
7 purchase totals =	$421.60		$467.3577	$467.37	$467.40	$467.30