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	$96.86	8.695%	$105.282	$105.28	$105.30	$105.30
Purchase #2	$55.58	3.322%	$57.4264	$57.43	$57.45	$57.40
Purchase #3	$66.42	9.790%	$72.9225	$72.92	$72.90	$72.90
Purchase #4	$196.32	12.596%	$221.0485	$221.05	$221.05	$221.00
Purchase #5	$228.88	8.436%	$248.1883	$248.19	$248.20	$248.20
Purchase #6	$69.60	8.809%	$75.7311	$75.73	$75.75	$75.70
Purchase #7	$220.89	8.179%	$238.9566	$238.96	$238.95	$239.00
7 purchase totals =	$934.55		$1,019.5554	$1,019.56	$1,019.60	$1,019.50