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	$200.31	5.824%	$211.9761	$211.98	$212.00	$212.00
Purchase #2	$63.35	5.109%	$66.5866	$66.59	$66.60	$66.60
Purchase #3	$135.89	6.760%	$145.0762	$145.08	$145.10	$145.10
Purchase #4	$231.83	8.187%	$250.8099	$250.81	$250.80	$250.80
Purchase #5	$164.65	8.728%	$179.0207	$179.02	$179.00	$179.00
Purchase #6	$52.82	12.633%	$59.4928	$59.49	$59.50	$59.50
Purchase #7	$103.71	8.575%	$112.6031	$112.60	$112.60	$112.60
7 purchase totals =	$952.56		$1,025.5654	$1,025.57	$1,025.60	$1,025.60