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	$168.71	10.652%	$186.681	$186.68	$186.70	$186.70
Purchase #2	$67.29	5.555%	$71.028	$71.03	$71.05	$71.00
Purchase #3	$44.69	9.384%	$48.8837	$48.88	$48.90	$48.90
Purchase #4	$57.32	3.570%	$59.3663	$59.37	$59.35	$59.40
Purchase #5	$225.36	8.606%	$244.7545	$244.75	$244.75	$244.80
Purchase #6	$169.85	7.412%	$182.4393	$182.44	$182.45	$182.40
Purchase #7	$203.60	10.308%	$224.5871	$224.59	$224.60	$224.60
7 purchase totals =	$936.82		$1,017.7399	$1,017.74	$1,017.80	$1,017.80