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	$86.76	10.275%	$95.6746	$95.67	$95.65	$95.70
Purchase #2	$175.77	13.858%	$200.1282	$200.13	$200.15	$200.10
Purchase #3	$36.33	11.826%	$40.6264	$40.63	$40.65	$40.60
Purchase #4	$220.76	12.700%	$248.7965	$248.80	$248.80	$248.80
Purchase #5	$137.76	10.685%	$152.4797	$152.48	$152.50	$152.50
Purchase #6	$49.84	6.526%	$53.0926	$53.09	$53.10	$53.10
Purchase #7	$219.44	9.508%	$240.3044	$240.30	$240.30	$240.30
7 purchase totals =	$926.66		$1,031.1024	$1,031.10	$1,031.15	$1,031.10