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	$40.63	12.439%	$45.684	$45.68	$45.70	$45.70
Purchase #2	$27.95	13.331%	$31.676	$31.68	$31.70	$31.70
Purchase #3	$84.81	5.357%	$89.3533	$89.35	$89.35	$89.40
Purchase #4	$250.33	3.397%	$258.8337	$258.83	$258.85	$258.80
Purchase #5	$80.32	12.830%	$90.6251	$90.63	$90.65	$90.60
Purchase #6	$183.64	5.662%	$194.0377	$194.04	$194.05	$194.00
Purchase #7	$229.40	3.622%	$237.7089	$237.71	$237.70	$237.70
7 purchase totals =	$897.08		$947.9187	$947.92	$948.00	$947.90