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	$162.45	5.319%	$171.0907	$171.09	$171.10	$171.10
Purchase #2	$134.96	5.365%	$142.2006	$142.20	$142.20	$142.20
Purchase #3	$237.65	3.396%	$245.7206	$245.72	$245.70	$245.70
Purchase #4	$88.76	4.425%	$92.6876	$92.69	$92.70	$92.70
Purchase #5	$90.82	10.384%	$100.2507	$100.25	$100.25	$100.30
Purchase #6	$238.74	5.215%	$251.1903	$251.19	$251.20	$251.20
Purchase #7	$174.36	12.521%	$196.1916	$196.19	$196.20	$196.20
7 purchase totals =	$1,127.74		$1,199.3321	$1,199.33	$1,199.35	$1,199.40