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	$107.68	5.829%	$113.9567	$113.96	$113.95	$114.00
Purchase #2	$84.59	6.203%	$89.8371	$89.84	$89.85	$89.80
Purchase #3	$204.90	7.102%	$219.452	$219.45	$219.45	$219.50
Purchase #4	$248.69	3.868%	$258.3093	$258.31	$258.30	$258.30
Purchase #5	$37.65	9.647%	$41.2821	$41.28	$41.30	$41.30
Purchase #6	$148.86	12.469%	$167.4214	$167.42	$167.40	$167.40
Purchase #7	$172.82	7.209%	$185.2786	$185.28	$185.30	$185.30
7 purchase totals =	$1,005.19		$1,075.5372	$1,075.54	$1,075.55	$1,075.60