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	$184.89	7.710%	$199.145	$199.15	$199.15	$199.10
Purchase #2	$52.95	7.375%	$56.8551	$56.86	$56.85	$56.90
Purchase #3	$132.89	11.551%	$148.2401	$148.24	$148.25	$148.20
Purchase #4	$116.83	6.521%	$124.4485	$124.45	$124.45	$124.40
Purchase #5	$142.65	5.791%	$150.9109	$150.91	$150.90	$150.90
Purchase #6	$150.86	3.597%	$156.2864	$156.29	$156.30	$156.30
Purchase #7	$241.30	11.355%	$268.6996	$268.70	$268.70	$268.70
7 purchase totals =	$1,022.37		$1,104.5856	$1,104.60	$1,104.60	$1,104.50