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	$144.40	4.261%	$150.5529	$150.55	$150.55	$150.60
Purchase #2	$35.76	4.347%	$37.3145	$37.31	$37.30	$37.30
Purchase #3	$84.32	7.570%	$90.703	$90.70	$90.70	$90.70
Purchase #4	$194.61	5.286%	$204.8971	$204.90	$204.90	$204.90
Purchase #5	$155.92	3.756%	$161.7764	$161.78	$161.80	$161.80
Purchase #6	$152.77	4.307%	$159.3498	$159.35	$159.35	$159.30
Purchase #7	$179.88	13.677%	$204.4822	$204.48	$204.50	$204.50
7 purchase totals =	$947.66		$1,009.0759	$1,009.07	$1,009.10	$1,009.10