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	$238.27	5.563%	$251.525	$251.53	$251.55	$251.50
Purchase #2	$31.71	6.496%	$33.7699	$33.77	$33.75	$33.80
Purchase #3	$52.90	8.394%	$57.3404	$57.34	$57.35	$57.30
Purchase #4	$238.53	5.126%	$250.757	$250.76	$250.75	$250.80
Purchase #5	$101.57	13.170%	$114.9468	$114.95	$114.95	$114.90
Purchase #6	$174.89	12.154%	$196.1461	$196.15	$196.15	$196.10
Purchase #7	$187.25	4.768%	$196.1781	$196.18	$196.20	$196.20
7 purchase totals =	$1,025.12		$1,100.6633	$1,100.68	$1,100.70	$1,100.60