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	$238.37	4.685%	$249.5376	$249.54	$249.55	$249.50
Purchase #2	$193.53	11.216%	$215.2363	$215.24	$215.25	$215.20
Purchase #3	$35.53	5.855%	$37.6103	$37.61	$37.60	$37.60
Purchase #4	$108.71	9.211%	$118.7233	$118.72	$118.70	$118.70
Purchase #5	$169.87	5.449%	$179.1262	$179.13	$179.15	$179.10
Purchase #6	$152.44	5.799%	$161.28	$161.28	$161.30	$161.30
Purchase #7	$146.26	6.290%	$155.4598	$155.46	$155.45	$155.50
7 purchase totals =	$1,044.71		$1,116.9735	$1,116.98	$1,117.00	$1,116.90