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	$54.27	4.557%	$56.7431	$56.74	$56.75	$56.70
Purchase #2	$120.75	9.862%	$132.6584	$132.66	$132.65	$132.70
Purchase #3	$14.75	4.284%	$15.3819	$15.38	$15.40	$15.40
Purchase #4	$211.96	5.390%	$223.3846	$223.38	$223.40	$223.40
Purchase #5	$16.37	13.686%	$18.6104	$18.61	$18.60	$18.60
Purchase #6	$209.28	3.558%	$216.7262	$216.73	$216.75	$216.70
Purchase #7	$57.49	3.515%	$59.5108	$59.51	$59.50	$59.50
7 purchase totals =	$684.87		$723.0154	$723.01	$723.05	$723.00