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	$103.27	5.871%	$109.333	$109.33	$109.35	$109.30
Purchase #2	$214.26	12.700%	$241.471	$241.47	$241.45	$241.50
Purchase #3	$209.98	6.837%	$224.3363	$224.34	$224.35	$224.30
Purchase #4	$170.93	3.390%	$176.7245	$176.72	$176.70	$176.70
Purchase #5	$215.57	5.241%	$226.868	$226.87	$226.85	$226.90
Purchase #6	$195.72	4.810%	$205.1341	$205.13	$205.15	$205.10
Purchase #7	$145.58	4.794%	$152.5591	$152.56	$152.55	$152.60
7 purchase totals =	$1,255.31		$1,336.4260	$1,336.42	$1,336.40	$1,336.40