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	$227.82	3.516%	$235.8302	$235.83	$235.85	$235.80
Purchase #2	$83.31	8.238%	$90.1731	$90.17	$90.15	$90.20
Purchase #3	$13.34	11.446%	$14.8669	$14.87	$14.85	$14.90
Purchase #4	$181.85	6.872%	$194.3467	$194.35	$194.35	$194.30
Purchase #5	$190.80	13.517%	$216.5904	$216.59	$216.60	$216.60
Purchase #6	$249.64	8.346%	$270.475	$270.48	$270.50	$270.50
Purchase #7	$164.50	8.519%	$178.5138	$178.51	$178.50	$178.50
7 purchase totals =	$1,111.26		$1,200.7961	$1,200.80	$1,200.80	$1,200.80