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	$178.30	10.464%	$196.9573	$196.96	$196.95	$197.00
Purchase #2	$148.97	13.302%	$168.786	$168.79	$168.80	$168.80
Purchase #3	$228.52	6.520%	$243.4195	$243.42	$243.40	$243.40
Purchase #4	$175.43	9.164%	$191.5064	$191.51	$191.50	$191.50
Purchase #5	$104.79	11.337%	$116.67	$116.67	$116.65	$116.70
Purchase #6	$98.46	13.810%	$112.0573	$112.06	$112.05	$112.10
Purchase #7	$132.27	4.386%	$138.0714	$138.07	$138.05	$138.10
7 purchase totals =	$1,066.74		$1,167.4679	$1,167.48	$1,167.40	$1,167.60