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	$143.84	4.750%	$150.6724	$150.67	$150.65	$150.70
Purchase #2	$120.83	3.328%	$124.8512	$124.85	$124.85	$124.90
Purchase #3	$101.86	3.620%	$105.5473	$105.55	$105.55	$105.50
Purchase #4	$29.49	8.163%	$31.8973	$31.90	$31.90	$31.90
Purchase #5	$85.75	9.109%	$93.561	$93.56	$93.55	$93.60
Purchase #6	$193.65	7.356%	$207.8949	$207.89	$207.90	$207.90
Purchase #7	$174.76	6.353%	$185.8625	$185.86	$185.85	$185.90
7 purchase totals =	$850.18		$900.2866	$900.28	$900.25	$900.40