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	$92.84	13.572%	$105.4402	$105.44	$105.45	$105.40
Purchase #2	$71.32	3.160%	$73.5737	$73.57	$73.55	$73.60
Purchase #3	$216.48	8.168%	$234.1621	$234.16	$234.15	$234.20
Purchase #4	$46.97	11.874%	$52.5472	$52.55	$52.55	$52.50
Purchase #5	$162.46	13.241%	$183.9713	$183.97	$183.95	$184.00
Purchase #6	$221.54	3.284%	$228.8154	$228.82	$228.80	$228.80
Purchase #7	$196.59	13.292%	$222.7207	$222.72	$222.70	$222.70
7 purchase totals =	$1,008.20		$1,101.2306	$1,101.23	$1,101.15	$1,101.20