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	$191.64	11.818%	$214.288	$214.29	$214.30	$214.30
Purchase #2	$164.40	3.144%	$169.5687	$169.57	$169.55	$169.60
Purchase #3	$134.30	9.413%	$146.9417	$146.94	$146.95	$146.90
Purchase #4	$157.86	5.824%	$167.0538	$167.05	$167.05	$167.10
Purchase #5	$86.57	10.224%	$95.4209	$95.42	$95.40	$95.40
Purchase #6	$56.40	7.233%	$60.4794	$60.48	$60.50	$60.50
Purchase #7	$149.81	12.502%	$168.5392	$168.54	$168.55	$168.50
7 purchase totals =	$940.98		$1,022.2917	$1,022.29	$1,022.30	$1,022.30