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	$156.68	5.252%	$164.9088	$164.91	$164.90	$164.90
Purchase #2	$104.48	5.248%	$109.9631	$109.96	$109.95	$110.00
Purchase #3	$159.40	7.446%	$171.2689	$171.27	$171.25	$171.30
Purchase #4	$203.39	12.291%	$228.3887	$228.39	$228.40	$228.40
Purchase #5	$223.83	13.424%	$253.8769	$253.88	$253.90	$253.90
Purchase #6	$141.27	12.187%	$158.4866	$158.49	$158.50	$158.50
Purchase #7	$98.35	5.687%	$103.9432	$103.94	$103.95	$103.90
7 purchase totals =	$1,087.40		$1,190.8362	$1,190.84	$1,190.85	$1,190.90