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	$75.92	13.735%	$86.3476	$86.35	$86.35	$86.30
Purchase #2	$176.56	11.514%	$196.8891	$196.89	$196.90	$196.90
Purchase #3	$170.77	5.788%	$180.6542	$180.65	$180.65	$180.70
Purchase #4	$250.92	5.401%	$264.4722	$264.47	$264.45	$264.50
Purchase #5	$135.71	8.328%	$147.0119	$147.01	$147.00	$147.00
Purchase #6	$78.87	6.217%	$83.7733	$83.77	$83.75	$83.80
Purchase #7	$59.46	10.127%	$65.4815	$65.48	$65.50	$65.50
7 purchase totals =	$948.21		$1,024.6298	$1,024.62	$1,024.60	$1,024.70