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	$172.62	12.798%	$194.7119	$194.71	$194.70	$194.70
Purchase #2	$135.61	10.664%	$150.0715	$150.07	$150.05	$150.10
Purchase #3	$33.35	6.324%	$35.4591	$35.46	$35.45	$35.50
Purchase #4	$53.30	10.841%	$59.0783	$59.08	$59.10	$59.10
Purchase #5	$234.36	5.836%	$248.0372	$248.04	$248.05	$248.00
Purchase #6	$176.59	8.703%	$191.9586	$191.96	$191.95	$192.00
Purchase #7	$177.69	4.308%	$185.3449	$185.34	$185.35	$185.30
7 purchase totals =	$983.52		$1,064.6615	$1,064.66	$1,064.65	$1,064.70