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	$111.80	3.782%	$116.0283	$116.03	$116.05	$116.00
Purchase #2	$94.40	6.507%	$100.5426	$100.54	$100.55	$100.50
Purchase #3	$11.66	7.467%	$12.5307	$12.53	$12.55	$12.50
Purchase #4	$205.99	6.634%	$219.6554	$219.66	$219.65	$219.70
Purchase #5	$63.95	11.483%	$71.2934	$71.29	$71.30	$71.30
Purchase #6	$13.98	9.227%	$15.2699	$15.27	$15.25	$15.30
Purchase #7	$191.56	9.632%	$210.0111	$210.01	$210.00	$210.00
7 purchase totals =	$693.34		$745.3314	$745.33	$745.35	$745.30