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	$215.41	11.526%	$240.2382	$240.24	$240.25	$240.20
Purchase #2	$33.48	10.300%	$36.9284	$36.93	$36.95	$36.90
Purchase #3	$50.65	8.618%	$55.015	$55.02	$55.00	$55.00
Purchase #4	$72.28	13.578%	$82.0942	$82.09	$82.10	$82.10
Purchase #5	$223.46	11.611%	$249.4059	$249.41	$249.40	$249.40
Purchase #6	$158.79	5.388%	$167.3456	$167.35	$167.35	$167.30
Purchase #7	$201.82	7.593%	$217.1442	$217.14	$217.15	$217.10
7 purchase totals =	$955.89		$1,048.1715	$1,048.18	$1,048.20	$1,048.00