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	$82.64	11.754%	$92.3535	$92.35	$92.35	$92.40
Purchase #2	$206.68	12.803%	$233.1412	$233.14	$233.15	$233.10
Purchase #3	$224.46	13.626%	$255.0449	$255.04	$255.05	$255.00
Purchase #4	$21.37	13.397%	$24.2329	$24.23	$24.25	$24.20
Purchase #5	$61.39	5.213%	$64.5903	$64.59	$64.60	$64.60
Purchase #6	$146.41	4.232%	$152.6061	$152.61	$152.60	$152.60
Purchase #7	$196.30	11.600%	$219.0708	$219.07	$219.05	$219.10
7 purchase totals =	$939.25		$1,041.0397	$1,041.03	$1,041.05	$1,041.00