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	$62.61	4.673%	$65.5358	$65.54	$65.55	$65.50
Purchase #2	$76.99	10.824%	$85.3234	$85.32	$85.30	$85.30
Purchase #3	$103.96	3.381%	$107.4749	$107.47	$107.45	$107.50
Purchase #4	$90.75	13.672%	$103.1573	$103.16	$103.15	$103.20
Purchase #5	$205.90	3.111%	$212.3055	$212.31	$212.30	$212.30
Purchase #6	$147.63	11.388%	$164.4421	$164.44	$164.45	$164.40
Purchase #7	$223.79	5.613%	$236.3513	$236.35	$236.35	$236.40
7 purchase totals =	$911.63		$974.5903	$974.59	$974.55	$974.60