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	$226.75	8.604%	$246.2596	$246.26	$246.25	$246.30
Purchase #2	$233.81	4.623%	$244.619	$244.62	$244.60	$244.60
Purchase #3	$173.72	7.546%	$186.8289	$186.83	$186.85	$186.80
Purchase #4	$216.36	3.283%	$223.4631	$223.46	$223.45	$223.50
Purchase #5	$90.61	8.754%	$98.542	$98.54	$98.55	$98.50
Purchase #6	$35.91	3.811%	$37.2785	$37.28	$37.30	$37.30
Purchase #7	$35.94	5.576%	$37.944	$37.94	$37.95	$37.90
7 purchase totals =	$1,013.10		$1,074.9351	$1,074.93	$1,074.95	$1,074.90