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	$41.36	7.319%	$44.3871	$44.39	$44.40	$44.40
Purchase #2	$71.31	10.396%	$78.7234	$78.72	$78.70	$78.70
Purchase #3	$145.70	4.593%	$152.392	$152.39	$152.40	$152.40
Purchase #4	$83.79	12.543%	$94.2998	$94.30	$94.30	$94.30
Purchase #5	$218.48	10.466%	$241.3461	$241.35	$241.35	$241.30
Purchase #6	$209.37	6.265%	$222.487	$222.49	$222.50	$222.50
Purchase #7	$162.60	5.836%	$172.0893	$172.09	$172.10	$172.10
7 purchase totals =	$932.61		$1,005.7247	$1,005.73	$1,005.75	$1,005.70