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	$57.25	10.296%	$63.1445	$63.14	$63.15	$63.10
Purchase #2	$56.55	10.852%	$62.6868	$62.69	$62.70	$62.70
Purchase #3	$69.56	4.859%	$72.9399	$72.94	$72.95	$72.90
Purchase #4	$33.48	10.507%	$36.9977	$37.00	$37.00	$37.00
Purchase #5	$244.74	13.486%	$277.7456	$277.75	$277.75	$277.70
Purchase #6	$86.62	11.331%	$96.4349	$96.43	$96.45	$96.40
Purchase #7	$137.69	3.331%	$142.2765	$142.28	$142.30	$142.30
7 purchase totals =	$685.89		$752.2259	$752.23	$752.30	$752.10