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	$162.38	10.215%	$178.9671	$178.97	$178.95	$179.00
Purchase #2	$106.44	6.237%	$113.0787	$113.08	$113.10	$113.10
Purchase #3	$152.28	8.657%	$165.4629	$165.46	$165.45	$165.50
Purchase #4	$209.43	6.215%	$222.4461	$222.45	$222.45	$222.40
Purchase #5	$204.74	10.151%	$225.5232	$225.52	$225.50	$225.50
Purchase #6	$42.93	4.813%	$44.9962	$45.00	$45.00	$45.00
Purchase #7	$53.40	10.561%	$59.0396	$59.04	$59.05	$59.00
7 purchase totals =	$931.60		$1,009.5138	$1,009.52	$1,009.50	$1,009.50