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	$107.27	3.508%	$111.033	$111.03	$111.05	$111.00
Purchase #2	$29.54	11.452%	$32.9229	$32.92	$32.90	$32.90
Purchase #3	$137.73	7.750%	$148.4041	$148.40	$148.40	$148.40
Purchase #4	$168.30	13.658%	$191.2864	$191.29	$191.30	$191.30
Purchase #5	$67.43	7.704%	$72.6248	$72.62	$72.60	$72.60
Purchase #6	$207.27	10.356%	$228.7349	$228.73	$228.75	$228.70
Purchase #7	$169.67	10.364%	$187.2546	$187.25	$187.25	$187.30
7 purchase totals =	$887.21		$972.2607	$972.24	$972.25	$972.20