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	$93.50	6.549%	$99.6233	$99.62	$99.60	$99.60
Purchase #2	$136.49	5.394%	$143.8523	$143.85	$143.85	$143.90
Purchase #3	$166.54	3.487%	$172.3472	$172.35	$172.35	$172.30
Purchase #4	$64.72	10.697%	$71.6431	$71.64	$71.65	$71.60
Purchase #5	$230.73	4.127%	$240.2522	$240.25	$240.25	$240.30
Purchase #6	$52.97	10.615%	$58.5928	$58.59	$58.60	$58.60
Purchase #7	$218.69	4.304%	$228.1024	$228.10	$228.10	$228.10
7 purchase totals =	$963.64		$1,014.4133	$1,014.40	$1,014.40	$1,014.40