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	$6.39	10.585%	$7.0664	$7.07	$7.05	$7.10
Purchase #2	$183.50	6.828%	$196.0294	$196.03	$196.05	$196.00
Purchase #3	$159.93	10.192%	$176.2301	$176.23	$176.25	$176.20
Purchase #4	$124.86	6.563%	$133.0546	$133.05	$133.05	$133.10
Purchase #5	$126.55	3.841%	$131.4108	$131.41	$131.40	$131.40
Purchase #6	$229.44	10.513%	$253.561	$253.56	$253.55	$253.60
Purchase #7	$156.82	5.120%	$164.8492	$164.85	$164.85	$164.80
7 purchase totals =	$987.49		$1,062.2015	$1,062.20	$1,062.20	$1,062.20