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	$176.73	10.136%	$194.6434	$194.64	$194.65	$194.60
Purchase #2	$152.44	13.194%	$172.5529	$172.55	$172.55	$172.60
Purchase #3	$72.98	8.176%	$78.9468	$78.95	$78.95	$78.90
Purchase #4	$68.89	10.182%	$75.9044	$75.90	$75.90	$75.90
Purchase #5	$142.63	11.749%	$159.3876	$159.39	$159.40	$159.40
Purchase #6	$182.76	12.356%	$205.3418	$205.34	$205.35	$205.30
Purchase #7	$148.37	13.477%	$168.3658	$168.37	$168.35	$168.40
7 purchase totals =	$944.80		$1,055.1427	$1,055.14	$1,055.15	$1,055.10