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	$229.63	6.521%	$244.6042	$244.60	$244.60	$244.60
Purchase #2	$244.25	6.380%	$259.8332	$259.83	$259.85	$259.80
Purchase #3	$86.66	13.483%	$98.3444	$98.34	$98.35	$98.30
Purchase #4	$73.37	11.840%	$82.057	$82.06	$82.05	$82.10
Purchase #5	$90.28	4.251%	$94.1178	$94.12	$94.10	$94.10
Purchase #6	$227.47	7.698%	$244.9806	$244.98	$245.00	$245.00
Purchase #7	$22.25	10.299%	$24.5415	$24.54	$24.55	$24.50
7 purchase totals =	$973.91		$1,048.4787	$1,048.47	$1,048.50	$1,048.40