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	$235.25	6.502%	$250.546	$250.55	$250.55	$250.50
Purchase #2	$22.72	6.659%	$24.2329	$24.23	$24.25	$24.20
Purchase #3	$90.31	11.600%	$100.786	$100.79	$100.80	$100.80
Purchase #4	$243.35	10.230%	$268.2447	$268.24	$268.25	$268.20
Purchase #5	$209.28	13.252%	$237.0138	$237.01	$237.00	$237.00
Purchase #6	$247.26	11.432%	$275.5268	$275.53	$275.55	$275.50
Purchase #7	$11.79	3.398%	$12.1906	$12.19	$12.20	$12.20
7 purchase totals =	$1,059.96		$1,168.5408	$1,168.54	$1,168.60	$1,168.40