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	$208.64	8.435%	$226.2388	$226.24	$226.25	$226.20
Purchase #2	$28.66	9.222%	$31.303	$31.30	$31.30	$31.30
Purchase #3	$52.90	6.429%	$56.3009	$56.30	$56.30	$56.30
Purchase #4	$79.32	13.519%	$90.0433	$90.04	$90.05	$90.00
Purchase #5	$173.81	3.132%	$179.2537	$179.25	$179.25	$179.30
Purchase #6	$58.43	4.467%	$61.0401	$61.04	$61.05	$61.00
Purchase #7	$159.90	12.164%	$179.3502	$179.35	$179.35	$179.40
7 purchase totals =	$761.66		$823.5300	$823.52	$823.55	$823.50