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	$178.70	10.154%	$196.8452	$196.85	$196.85	$196.80
Purchase #2	$243.72	7.469%	$261.9234	$261.92	$261.90	$261.90
Purchase #3	$86.90	9.344%	$95.0199	$95.02	$95.00	$95.00
Purchase #4	$125.44	5.590%	$132.4521	$132.45	$132.45	$132.50
Purchase #5	$149.74	4.570%	$156.5831	$156.58	$156.60	$156.60
Purchase #6	$190.28	5.244%	$200.2583	$200.26	$200.25	$200.30
Purchase #7	$157.83	13.684%	$179.4275	$179.43	$179.45	$179.40
7 purchase totals =	$1,132.61		$1,222.5095	$1,222.51	$1,222.50	$1,222.50