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	$181.32	10.109%	$199.6496	$199.65	$199.65	$199.60
Purchase #2	$27.29	5.118%	$28.6867	$28.69	$28.70	$28.70
Purchase #3	$17.71	4.425%	$18.4937	$18.49	$18.50	$18.50
Purchase #4	$147.85	11.138%	$164.3175	$164.32	$164.30	$164.30
Purchase #5	$118.33	11.126%	$131.4954	$131.50	$131.50	$131.50
Purchase #6	$42.30	8.496%	$45.8938	$45.89	$45.90	$45.90
Purchase #7	$178.84	10.845%	$198.2352	$198.24	$198.25	$198.20
7 purchase totals =	$713.64		$786.7719	$786.78	$786.80	$786.70