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	$125.34	13.364%	$142.0904	$142.09	$142.10	$142.10
Purchase #2	$94.78	4.497%	$99.0423	$99.04	$99.05	$99.00
Purchase #3	$145.97	4.708%	$152.8423	$152.84	$152.85	$152.80
Purchase #4	$134.59	3.317%	$139.0544	$139.05	$139.05	$139.10
Purchase #5	$97.43	8.143%	$105.3637	$105.36	$105.35	$105.40
Purchase #6	$246.99	3.351%	$255.2666	$255.27	$255.25	$255.30
Purchase #7	$211.44	6.256%	$224.6677	$224.67	$224.65	$224.70
7 purchase totals =	$1,056.54		$1,118.3274	$1,118.32	$1,118.30	$1,118.40