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	$82.72	3.445%	$85.5697	$85.57	$85.55	$85.60
Purchase #2	$31.77	6.688%	$33.8948	$33.89	$33.90	$33.90
Purchase #3	$37.50	10.306%	$41.3648	$41.36	$41.35	$41.40
Purchase #4	$78.69	10.451%	$86.9139	$86.91	$86.90	$86.90
Purchase #5	$166.78	3.669%	$172.8992	$172.90	$172.90	$172.90
Purchase #6	$149.86	6.643%	$159.8152	$159.82	$159.80	$159.80
Purchase #7	$114.36	10.843%	$126.7601	$126.76	$126.75	$126.80
7 purchase totals =	$661.68		$707.2177	$707.21	$707.15	$707.30