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	$197.46	12.402%	$221.949	$221.95	$221.95	$221.90
Purchase #2	$122.38	7.806%	$131.933	$131.93	$131.95	$131.90
Purchase #3	$105.75	4.423%	$110.4273	$110.43	$110.45	$110.40
Purchase #4	$78.34	9.778%	$86.0001	$86.00	$86.00	$86.00
Purchase #5	$80.98	12.574%	$91.1624	$91.16	$91.15	$91.20
Purchase #6	$206.67	8.199%	$223.6149	$223.61	$223.60	$223.60
Purchase #7	$160.31	13.567%	$182.0593	$182.06	$182.05	$182.10
7 purchase totals =	$951.89		$1,047.1460	$1,047.14	$1,047.15	$1,047.10