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	$106.61	4.209%	$111.0972	$111.10	$111.10	$111.10
Purchase #2	$15.74	10.660%	$17.4179	$17.42	$17.40	$17.40
Purchase #3	$27.37	5.176%	$28.7867	$28.79	$28.80	$28.80
Purchase #4	$59.98	11.800%	$67.0576	$67.06	$67.05	$67.10
Purchase #5	$164.38	10.286%	$181.2881	$181.29	$181.30	$181.30
Purchase #6	$79.43	11.166%	$88.2992	$88.30	$88.30	$88.30
Purchase #7	$199.96	10.682%	$221.3197	$221.32	$221.30	$221.30
7 purchase totals =	$653.47		$715.2664	$715.28	$715.25	$715.30