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	$222.56	9.380%	$243.4361	$243.44	$243.45	$243.40
Purchase #2	$52.93	3.477%	$54.7704	$54.77	$54.75	$54.80
Purchase #3	$156.63	6.712%	$167.143	$167.14	$167.15	$167.10
Purchase #4	$154.49	6.760%	$164.9335	$164.93	$164.95	$164.90
Purchase #5	$151.56	6.801%	$161.8676	$161.87	$161.85	$161.90
Purchase #6	$203.65	9.445%	$222.8847	$222.88	$222.90	$222.90
Purchase #7	$140.47	3.667%	$145.621	$145.62	$145.60	$145.60
7 purchase totals =	$1,082.29		$1,160.6563	$1,160.65	$1,160.65	$1,160.60