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	$148.41	5.223%	$156.1615	$156.16	$156.15	$156.20
Purchase #2	$223.76	3.486%	$231.5603	$231.56	$231.55	$231.60
Purchase #3	$31.33	5.131%	$32.9375	$32.94	$32.95	$32.90
Purchase #4	$127.32	13.230%	$144.1644	$144.16	$144.15	$144.20
Purchase #5	$39.72	3.525%	$41.1201	$41.12	$41.10	$41.10
Purchase #6	$225.92	9.523%	$247.4344	$247.43	$247.45	$247.40
Purchase #7	$219.30	10.233%	$241.741	$241.74	$241.75	$241.70
7 purchase totals =	$1,015.76		$1,095.1192	$1,095.11	$1,095.10	$1,095.10