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	$188.47	4.367%	$196.7005	$196.70	$196.70	$196.70
Purchase #2	$77.68	8.340%	$84.1585	$84.16	$84.15	$84.20
Purchase #3	$7.99	11.187%	$8.8838	$8.88	$8.90	$8.90
Purchase #4	$5.88	11.784%	$6.5729	$6.57	$6.55	$6.60
Purchase #5	$86.27	4.150%	$89.8502	$89.85	$89.85	$89.90
Purchase #6	$217.67	9.618%	$238.6055	$238.61	$238.60	$238.60
Purchase #7	$84.47	5.538%	$89.1479	$89.15	$89.15	$89.10
7 purchase totals =	$668.43		$713.9193	$713.92	$713.90	$714.00