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	$174.84	13.184%	$197.8909	$197.89	$197.90	$197.90
Purchase #2	$38.79	11.538%	$43.2656	$43.27	$43.25	$43.30
Purchase #3	$199.34	6.417%	$212.1316	$212.13	$212.15	$212.10
Purchase #4	$165.90	3.829%	$172.2523	$172.25	$172.25	$172.30
Purchase #5	$91.93	7.324%	$98.663	$98.66	$98.65	$98.70
Purchase #6	$188.69	5.686%	$199.4189	$199.42	$199.40	$199.40
Purchase #7	$186.46	9.348%	$203.8903	$203.89	$203.90	$203.90
7 purchase totals =	$1,045.95		$1,127.5126	$1,127.51	$1,127.50	$1,127.60