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	$167.94	3.510%	$173.8347	$173.83	$173.85	$173.80
Purchase #2	$202.79	3.110%	$209.0968	$209.10	$209.10	$209.10
Purchase #3	$176.46	11.134%	$196.1071	$196.11	$196.10	$196.10
Purchase #4	$48.37	5.770%	$51.1609	$51.16	$51.15	$51.20
Purchase #5	$158.29	3.547%	$163.9045	$163.90	$163.90	$163.90
Purchase #6	$151.82	3.109%	$156.5401	$156.54	$156.55	$156.50
Purchase #7	$178.91	7.166%	$191.7307	$191.73	$191.75	$191.70
7 purchase totals =	$1,084.58		$1,142.3748	$1,142.37	$1,142.40	$1,142.30