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	$211.70	5.835%	$224.0527	$224.05	$224.05	$224.10
Purchase #2	$187.29	7.176%	$200.7299	$200.73	$200.75	$200.70
Purchase #3	$164.95	5.439%	$173.9216	$173.92	$173.90	$173.90
Purchase #4	$173.79	4.191%	$181.0735	$181.07	$181.05	$181.10
Purchase #5	$136.41	11.811%	$152.5214	$152.52	$152.50	$152.50
Purchase #6	$44.39	6.653%	$47.3433	$47.34	$47.35	$47.30
Purchase #7	$106.38	5.151%	$111.8596	$111.86	$111.85	$111.90
7 purchase totals =	$1,024.91		$1,091.5020	$1,091.49	$1,091.45	$1,091.50