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	$194.34	7.329%	$208.5832	$208.58	$208.60	$208.60
Purchase #2	$63.96	13.659%	$72.6963	$72.70	$72.70	$72.70
Purchase #3	$214.42	12.723%	$241.7007	$241.70	$241.70	$241.70
Purchase #4	$132.72	6.695%	$141.6056	$141.61	$141.60	$141.60
Purchase #5	$124.40	6.126%	$132.0207	$132.02	$132.00	$132.00
Purchase #6	$99.92	3.639%	$103.5561	$103.56	$103.55	$103.60
Purchase #7	$185.34	3.575%	$191.9659	$191.97	$191.95	$192.00
7 purchase totals =	$1,015.10		$1,092.1285	$1,092.14	$1,092.10	$1,092.20