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	$158.61	5.694%	$167.6413	$167.64	$167.65	$167.60
Purchase #2	$150.27	7.193%	$161.0789	$161.08	$161.10	$161.10
Purchase #3	$53.81	7.712%	$57.9598	$57.96	$57.95	$58.00
Purchase #4	$99.33	12.168%	$111.4165	$111.42	$111.40	$111.40
Purchase #5	$174.36	6.855%	$186.3124	$186.31	$186.30	$186.30
Purchase #6	$186.87	4.854%	$195.9407	$195.94	$195.95	$195.90
Purchase #7	$125.86	4.181%	$131.1222	$131.12	$131.10	$131.10
7 purchase totals =	$949.11		$1,011.4718	$1,011.47	$1,011.45	$1,011.40