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	$64.79	11.241%	$72.073	$72.07	$72.05	$72.10
Purchase #2	$110.51	5.738%	$116.8511	$116.85	$116.85	$116.90
Purchase #3	$50.98	11.711%	$56.9503	$56.95	$56.95	$57.00
Purchase #4	$158.66	9.750%	$174.1294	$174.13	$174.15	$174.10
Purchase #5	$249.61	10.324%	$275.3797	$275.38	$275.40	$275.40
Purchase #6	$162.95	10.184%	$179.5448	$179.54	$179.55	$179.50
Purchase #7	$120.64	13.130%	$136.48	$136.48	$136.50	$136.50
7 purchase totals =	$918.14		$1,011.4083	$1,011.40	$1,011.45	$1,011.50