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	$39.28	5.816%	$41.5645	$41.56	$41.55	$41.60
Purchase #2	$228.31	11.151%	$253.7688	$253.77	$253.75	$253.80
Purchase #3	$87.68	10.535%	$96.9171	$96.92	$96.90	$96.90
Purchase #4	$140.42	8.184%	$151.912	$151.91	$151.90	$151.90
Purchase #5	$220.67	10.834%	$244.5774	$244.58	$244.60	$244.60
Purchase #6	$42.78	10.192%	$47.1401	$47.14	$47.15	$47.10
Purchase #7	$209.97	7.616%	$225.9613	$225.96	$225.95	$226.00
7 purchase totals =	$969.11		$1,061.8412	$1,061.84	$1,061.80	$1,061.90