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	$62.88	13.563%	$71.4084	$71.41	$71.40	$71.40
Purchase #2	$12.64	7.472%	$13.5845	$13.58	$13.60	$13.60
Purchase #3	$30.80	8.438%	$33.3989	$33.40	$33.40	$33.40
Purchase #4	$46.32	5.411%	$48.8264	$48.83	$48.85	$48.80
Purchase #5	$81.33	12.257%	$91.2986	$91.30	$91.30	$91.30
Purchase #6	$162.36	5.503%	$171.2947	$171.29	$171.30	$171.30
Purchase #7	$183.85	11.280%	$204.5883	$204.59	$204.60	$204.60
7 purchase totals =	$580.18		$634.3998	$634.40	$634.45	$634.40