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	$227.50	7.455%	$244.4601	$244.46	$244.45	$244.50
Purchase #2	$178.36	7.662%	$192.0259	$192.03	$192.05	$192.00
Purchase #3	$32.91	13.123%	$37.2288	$37.23	$37.25	$37.20
Purchase #4	$218.62	7.577%	$235.1848	$235.18	$235.20	$235.20
Purchase #5	$200.96	4.293%	$209.5872	$209.59	$209.60	$209.60
Purchase #6	$66.40	9.111%	$72.4497	$72.45	$72.45	$72.40
Purchase #7	$152.85	5.545%	$161.3255	$161.33	$161.35	$161.30
7 purchase totals =	$1,077.60		$1,152.2620	$1,152.27	$1,152.35	$1,152.20