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	$217.37	7.552%	$233.7858	$233.79	$233.80	$233.80
Purchase #2	$85.52	11.455%	$95.3163	$95.32	$95.30	$95.30
Purchase #3	$173.53	3.852%	$180.2144	$180.21	$180.20	$180.20
Purchase #4	$239.77	8.243%	$259.5342	$259.53	$259.55	$259.50
Purchase #5	$53.89	6.661%	$57.4796	$57.48	$57.50	$57.50
Purchase #6	$10.37	8.362%	$11.2371	$11.24	$11.25	$11.20
Purchase #7	$83.89	8.420%	$90.9535	$90.95	$90.95	$91.00
7 purchase totals =	$864.34		$928.5209	$928.52	$928.55	$928.50