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	$200.60	11.333%	$223.334	$223.33	$223.35	$223.30
Purchase #2	$119.55	11.669%	$133.5003	$133.50	$133.50	$133.50
Purchase #3	$5.63	9.216%	$6.1489	$6.15	$6.15	$6.10
Purchase #4	$98.28	7.183%	$105.3395	$105.34	$105.35	$105.30
Purchase #5	$167.61	13.244%	$189.8083	$189.81	$189.80	$189.80
Purchase #6	$76.33	12.321%	$85.7346	$85.73	$85.75	$85.70
Purchase #7	$43.32	11.392%	$48.255	$48.26	$48.25	$48.30
7 purchase totals =	$711.32		$792.1206	$792.12	$792.15	$792.00