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	$151.34	11.449%	$168.6669	$168.67	$168.65	$168.70
Purchase #2	$147.61	3.195%	$152.3261	$152.33	$152.35	$152.30
Purchase #3	$179.36	6.734%	$191.4381	$191.44	$191.45	$191.40
Purchase #4	$179.49	3.594%	$185.9409	$185.94	$185.95	$185.90
Purchase #5	$16.90	4.706%	$17.6953	$17.70	$17.70	$17.70
Purchase #6	$152.97	3.510%	$158.3392	$158.34	$158.35	$158.30
Purchase #7	$130.49	11.207%	$145.114	$145.11	$145.10	$145.10
7 purchase totals =	$958.16		$1,019.5205	$1,019.53	$1,019.55	$1,019.40