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	$174.30	6.359%	$185.3837	$185.38	$185.40	$185.40
Purchase #2	$159.71	7.259%	$171.3033	$171.30	$171.30	$171.30
Purchase #3	$31.89	13.858%	$36.3093	$36.31	$36.30	$36.30
Purchase #4	$156.76	11.258%	$174.408	$174.41	$174.40	$174.40
Purchase #5	$148.43	13.835%	$168.9653	$168.97	$168.95	$169.00
Purchase #6	$147.48	4.333%	$153.8703	$153.87	$153.85	$153.90
Purchase #7	$168.29	5.747%	$177.9616	$177.96	$177.95	$178.00
7 purchase totals =	$986.86		$1,068.2015	$1,068.20	$1,068.15	$1,068.30