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	$167.37	4.460%	$174.8347	$174.83	$174.85	$174.80
Purchase #2	$180.54	3.382%	$186.6459	$186.65	$186.65	$186.60
Purchase #3	$146.76	6.336%	$156.0587	$156.06	$156.05	$156.10
Purchase #4	$120.67	5.820%	$127.693	$127.69	$127.70	$127.70
Purchase #5	$98.64	11.238%	$109.7252	$109.73	$109.75	$109.70
Purchase #6	$170.32	4.228%	$177.5211	$177.52	$177.50	$177.50
Purchase #7	$215.64	6.387%	$229.4129	$229.41	$229.40	$229.40
7 purchase totals =	$1,099.94		$1,161.8915	$1,161.89	$1,161.90	$1,161.80