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	$167.77	8.824%	$182.574	$182.57	$182.55	$182.60
Purchase #2	$63.46	6.514%	$67.5938	$67.59	$67.60	$67.60
Purchase #3	$219.68	10.611%	$242.9902	$242.99	$243.00	$243.00
Purchase #4	$142.66	5.771%	$150.8929	$150.89	$150.90	$150.90
Purchase #5	$56.40	9.843%	$61.9515	$61.95	$61.95	$62.00
Purchase #6	$212.37	11.705%	$237.2279	$237.23	$237.25	$237.20
Purchase #7	$116.60	11.826%	$130.3891	$130.39	$130.40	$130.40
7 purchase totals =	$978.94		$1,073.6194	$1,073.61	$1,073.65	$1,073.70