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	$145.84	6.778%	$155.725	$155.73	$155.75	$155.70
Purchase #2	$73.82	11.841%	$82.561	$82.56	$82.55	$82.60
Purchase #3	$193.36	9.134%	$211.0215	$211.02	$211.00	$211.00
Purchase #4	$222.27	7.254%	$238.3935	$238.39	$238.40	$238.40
Purchase #5	$111.90	5.147%	$117.6595	$117.66	$117.65	$117.70
Purchase #6	$141.68	8.383%	$153.557	$153.56	$153.55	$153.60
Purchase #7	$99.85	11.185%	$111.0182	$111.02	$111.00	$111.00
7 purchase totals =	$988.72		$1,069.9357	$1,069.94	$1,069.90	$1,070.00