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	$190.86	5.261%	$200.9011	$200.90	$200.90	$200.90
Purchase #2	$19.65	11.375%	$21.8852	$21.89	$21.90	$21.90
Purchase #3	$189.51	9.835%	$208.1483	$208.15	$208.15	$208.10
Purchase #4	$164.66	8.871%	$179.267	$179.27	$179.25	$179.30
Purchase #5	$17.84	13.522%	$20.2523	$20.25	$20.25	$20.30
Purchase #6	$143.54	10.696%	$158.893	$158.89	$158.90	$158.90
Purchase #7	$209.78	8.694%	$228.0183	$228.02	$228.00	$228.00
7 purchase totals =	$935.84		$1,017.3652	$1,017.37	$1,017.35	$1,017.40