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	$77.85	11.222%	$86.5863	$86.59	$86.60	$86.60
Purchase #2	$203.27	6.391%	$216.261	$216.26	$216.25	$216.30
Purchase #3	$167.52	3.816%	$173.9126	$173.91	$173.90	$173.90
Purchase #4	$24.51	3.490%	$25.3654	$25.37	$25.35	$25.40
Purchase #5	$51.67	13.179%	$58.4796	$58.48	$58.50	$58.50
Purchase #6	$187.50	3.646%	$194.3363	$194.34	$194.35	$194.30
Purchase #7	$235.94	10.779%	$261.372	$261.37	$261.35	$261.40
7 purchase totals =	$948.26		$1,016.3132	$1,016.32	$1,016.30	$1,016.40