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	$191.72	11.215%	$213.2214	$213.22	$213.20	$213.20
Purchase #2	$199.71	11.470%	$222.6167	$222.62	$222.60	$222.60
Purchase #3	$18.56	5.869%	$19.6493	$19.65	$19.65	$19.60
Purchase #4	$51.82	5.330%	$54.582	$54.58	$54.60	$54.60
Purchase #5	$245.54	8.760%	$267.0493	$267.05	$267.05	$267.00
Purchase #6	$88.84	12.349%	$99.8109	$99.81	$99.80	$99.80
Purchase #7	$225.46	11.206%	$250.725	$250.73	$250.75	$250.70
7 purchase totals =	$1,021.65		$1,127.6546	$1,127.66	$1,127.65	$1,127.50