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	$156.46	7.102%	$167.5718	$167.57	$167.55	$167.60
Purchase #2	$11.89	5.482%	$12.5418	$12.54	$12.55	$12.50
Purchase #3	$146.97	6.583%	$156.645	$156.65	$156.65	$156.60
Purchase #4	$95.79	5.294%	$100.8611	$100.86	$100.85	$100.90
Purchase #5	$148.77	9.337%	$162.6607	$162.66	$162.65	$162.70
Purchase #6	$243.57	7.267%	$261.2702	$261.27	$261.25	$261.30
Purchase #7	$140.80	13.555%	$159.8854	$159.89	$159.90	$159.90
7 purchase totals =	$944.25		$1,021.4360	$1,021.44	$1,021.40	$1,021.50