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	$98.45	5.449%	$103.8145	$103.81	$103.80	$103.80
Purchase #2	$77.69	6.248%	$82.5441	$82.54	$82.55	$82.50
Purchase #3	$100.95	9.718%	$110.7603	$110.76	$110.75	$110.80
Purchase #4	$219.38	3.634%	$227.3523	$227.35	$227.35	$227.40
Purchase #5	$99.74	13.282%	$112.9875	$112.99	$113.00	$113.00
Purchase #6	$174.45	4.663%	$182.5846	$182.58	$182.60	$182.60
Purchase #7	$216.68	11.398%	$241.3772	$241.38	$241.40	$241.40
7 purchase totals =	$987.34		$1,061.4205	$1,061.41	$1,061.45	$1,061.50