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	$181.64	8.211%	$196.5545	$196.55	$196.55	$196.60
Purchase #2	$234.71	13.223%	$265.7457	$265.75	$265.75	$265.70
Purchase #3	$30.68	4.640%	$32.1036	$32.10	$32.10	$32.10
Purchase #4	$195.30	12.559%	$219.8277	$219.83	$219.85	$219.80
Purchase #5	$146.86	6.603%	$156.5572	$156.56	$156.55	$156.60
Purchase #6	$17.32	4.234%	$18.0533	$18.05	$18.05	$18.10
Purchase #7	$20.83	12.308%	$23.3938	$23.39	$23.40	$23.40
7 purchase totals =	$827.34		$912.2358	$912.23	$912.25	$912.30