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	$185.94	5.607%	$196.3657	$196.37	$196.35	$196.40
Purchase #2	$203.74	11.472%	$227.1131	$227.11	$227.10	$227.10
Purchase #3	$37.91	8.557%	$41.154	$41.15	$41.15	$41.20
Purchase #4	$85.30	13.143%	$96.511	$96.51	$96.50	$96.50
Purchase #5	$172.44	5.507%	$181.9363	$181.94	$181.95	$181.90
Purchase #6	$96.63	5.413%	$101.8606	$101.86	$101.85	$101.90
Purchase #7	$167.26	9.157%	$182.576	$182.58	$182.60	$182.60
7 purchase totals =	$949.22		$1,027.5167	$1,027.52	$1,027.50	$1,027.60