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	$163.62	6.416%	$174.1179	$174.12	$174.10	$174.10
Purchase #2	$142.77	7.138%	$152.9609	$152.96	$152.95	$153.00
Purchase #3	$203.66	9.480%	$222.967	$222.97	$222.95	$223.00
Purchase #4	$130.29	11.747%	$145.5952	$145.60	$145.60	$145.60
Purchase #5	$19.96	4.259%	$20.8101	$20.81	$20.80	$20.80
Purchase #6	$237.37	3.588%	$245.8868	$245.89	$245.90	$245.90
Purchase #7	$49.33	9.202%	$53.8693	$53.87	$53.85	$53.90
7 purchase totals =	$947.00		$1,016.2072	$1,016.22	$1,016.15	$1,016.30