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	$118.28	7.481%	$127.1285	$127.13	$127.15	$127.10
Purchase #2	$97.75	7.435%	$105.0177	$105.02	$105.00	$105.00
Purchase #3	$31.52	12.304%	$35.3982	$35.40	$35.40	$35.40
Purchase #4	$28.95	5.141%	$30.4383	$30.44	$30.45	$30.40
Purchase #5	$104.94	9.420%	$114.8253	$114.83	$114.85	$114.80
Purchase #6	$157.59	3.308%	$162.8031	$162.80	$162.80	$162.80
Purchase #7	$191.33	9.518%	$209.5408	$209.54	$209.55	$209.50
7 purchase totals =	$730.36		$785.1519	$785.16	$785.20	$785.00