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	$85.48	7.722%	$92.0808	$92.08	$92.10	$92.10
Purchase #2	$156.66	7.628%	$168.61	$168.61	$168.60	$168.60
Purchase #3	$183.74	13.735%	$208.9767	$208.98	$209.00	$209.00
Purchase #4	$205.83	8.770%	$223.8813	$223.88	$223.90	$223.90
Purchase #5	$26.49	10.185%	$29.188	$29.19	$29.20	$29.20
Purchase #6	$129.61	10.257%	$142.9041	$142.90	$142.90	$142.90
Purchase #7	$162.75	3.177%	$167.9206	$167.92	$167.90	$167.90
7 purchase totals =	$950.56		$1,033.5615	$1,033.56	$1,033.60	$1,033.60