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	$172.82	11.593%	$192.855	$192.86	$192.85	$192.90
Purchase #2	$109.76	12.723%	$123.7248	$123.72	$123.70	$123.70
Purchase #3	$53.97	9.663%	$59.1851	$59.19	$59.20	$59.20
Purchase #4	$207.62	7.375%	$222.932	$222.93	$222.95	$222.90
Purchase #5	$47.31	6.410%	$50.3426	$50.34	$50.35	$50.30
Purchase #6	$216.64	4.302%	$225.9599	$225.96	$225.95	$226.00
Purchase #7	$72.93	9.690%	$79.9969	$80.00	$80.00	$80.00
7 purchase totals =	$881.05		$954.9963	$955.00	$955.00	$955.00