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	$63.67	5.666%	$67.2775	$67.28	$67.30	$67.30
Purchase #2	$16.28	3.541%	$16.8565	$16.86	$16.85	$16.90
Purchase #3	$38.76	13.226%	$43.8864	$43.89	$43.90	$43.90
Purchase #4	$129.83	7.469%	$139.527	$139.53	$139.55	$139.50
Purchase #5	$61.49	10.243%	$67.7884	$67.79	$67.80	$67.80
Purchase #6	$211.38	6.386%	$224.8787	$224.88	$224.90	$224.90
Purchase #7	$202.81	6.755%	$216.5098	$216.51	$216.50	$216.50
7 purchase totals =	$724.22		$776.7243	$776.74	$776.80	$776.80