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	$194.32	7.802%	$209.4808	$209.48	$209.50	$209.50
Purchase #2	$150.59	13.810%	$171.3865	$171.39	$171.40	$171.40
Purchase #3	$78.87	4.432%	$82.3655	$82.37	$82.35	$82.40
Purchase #4	$211.33	5.360%	$222.6573	$222.66	$222.65	$222.70
Purchase #5	$225.53	10.521%	$249.258	$249.26	$249.25	$249.30
Purchase #6	$215.84	8.713%	$234.6461	$234.65	$234.65	$234.60
Purchase #7	$53.54	6.779%	$57.1695	$57.17	$57.15	$57.20
7 purchase totals =	$1,130.02		$1,226.9637	$1,226.98	$1,226.95	$1,227.10