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	$222.47	9.643%	$243.9228	$243.92	$243.90	$243.90
Purchase #2	$231.69	4.464%	$242.0326	$242.03	$242.05	$242.00
Purchase #3	$150.95	13.304%	$171.0324	$171.03	$171.05	$171.00
Purchase #4	$18.45	12.162%	$20.6939	$20.69	$20.70	$20.70
Purchase #5	$33.72	8.570%	$36.6098	$36.61	$36.60	$36.60
Purchase #6	$51.35	4.226%	$53.5201	$53.52	$53.50	$53.50
Purchase #7	$240.48	7.684%	$258.9585	$258.96	$258.95	$259.00
7 purchase totals =	$949.11		$1,026.7701	$1,026.76	$1,026.75	$1,026.70