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	$181.69	8.249%	$196.6776	$196.68	$196.70	$196.70
Purchase #2	$127.32	3.253%	$131.4617	$131.46	$131.45	$131.50
Purchase #3	$28.75	3.355%	$29.7146	$29.71	$29.70	$29.70
Purchase #4	$157.80	6.832%	$168.5809	$168.58	$168.60	$168.60
Purchase #5	$108.64	8.479%	$117.8516	$117.85	$117.85	$117.90
Purchase #6	$209.38	8.774%	$227.751	$227.75	$227.75	$227.80
Purchase #7	$28.84	11.376%	$32.1208	$32.12	$32.10	$32.10
7 purchase totals =	$842.42		$904.1582	$904.15	$904.15	$904.30