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	$88.28	6.757%	$94.2451	$94.25	$94.25	$94.20
Purchase #2	$73.86	6.290%	$78.5058	$78.51	$78.50	$78.50
Purchase #3	$43.38	5.546%	$45.7859	$45.79	$45.80	$45.80
Purchase #4	$5.95	7.136%	$6.3746	$6.37	$6.35	$6.40
Purchase #5	$7.39	11.662%	$8.2518	$8.25	$8.25	$8.30
Purchase #6	$119.55	11.208%	$132.9492	$132.95	$132.95	$132.90
Purchase #7	$42.28	4.752%	$44.2891	$44.29	$44.30	$44.30
7 purchase totals =	$380.69		$410.4015	$410.41	$410.40	$410.40