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	$13.37	5.796%	$14.1449	$14.14	$14.15	$14.10
Purchase #2	$82.70	7.661%	$89.0356	$89.04	$89.05	$89.00
Purchase #3	$172.73	13.261%	$195.6357	$195.64	$195.65	$195.60
Purchase #4	$238.98	9.688%	$262.1324	$262.13	$262.15	$262.10
Purchase #5	$124.56	4.441%	$130.0917	$130.09	$130.10	$130.10
Purchase #6	$166.42	9.293%	$181.8854	$181.89	$181.90	$181.90
Purchase #7	$126.27	4.476%	$131.9218	$131.92	$131.90	$131.90
7 purchase totals =	$925.03		$1,004.8475	$1,004.85	$1,004.90	$1,004.70