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	$96.40	7.318%	$103.4546	$103.45	$103.45	$103.50
Purchase #2	$174.33	5.737%	$184.3313	$184.33	$184.35	$184.30
Purchase #3	$91.94	12.273%	$103.2238	$103.22	$103.20	$103.20
Purchase #4	$185.83	13.343%	$210.6253	$210.63	$210.65	$210.60
Purchase #5	$186.26	3.272%	$192.3544	$192.35	$192.35	$192.40
Purchase #6	$131.74	11.502%	$146.8927	$146.89	$146.90	$146.90
Purchase #7	$75.41	12.793%	$85.0572	$85.06	$85.05	$85.10
7 purchase totals =	$941.91		$1,025.9393	$1,025.93	$1,025.95	$1,026.00