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	$196.56	13.327%	$222.7556	$222.76	$222.75	$222.80
Purchase #2	$9.35	13.479%	$10.6103	$10.61	$10.60	$10.60
Purchase #3	$119.63	6.756%	$127.7122	$127.71	$127.70	$127.70
Purchase #4	$160.30	11.300%	$178.4139	$178.41	$178.40	$178.40
Purchase #5	$124.79	6.381%	$132.7528	$132.75	$132.75	$132.80
Purchase #6	$205.32	3.856%	$213.2371	$213.24	$213.25	$213.20
Purchase #7	$67.64	3.659%	$70.1149	$70.11	$70.10	$70.10
7 purchase totals =	$883.59		$955.5968	$955.59	$955.55	$955.60