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	$211.61	5.408%	$223.0539	$223.05	$223.05	$223.10
Purchase #2	$97.35	6.570%	$103.7459	$103.75	$103.75	$103.70
Purchase #3	$130.85	6.243%	$139.019	$139.02	$139.00	$139.00
Purchase #4	$103.69	9.444%	$113.4825	$113.48	$113.50	$113.50
Purchase #5	$143.32	10.796%	$158.7928	$158.79	$158.80	$158.80
Purchase #6	$109.61	3.600%	$113.556	$113.56	$113.55	$113.60
Purchase #7	$76.78	6.317%	$81.6302	$81.63	$81.65	$81.60
7 purchase totals =	$873.21		$933.2803	$933.28	$933.30	$933.30