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	$116.32	9.419%	$127.2762	$127.28	$127.30	$127.30
Purchase #2	$114.44	9.538%	$125.3553	$125.36	$125.35	$125.40
Purchase #3	$213.92	9.143%	$233.4787	$233.48	$233.50	$233.50
Purchase #4	$143.84	8.227%	$155.6737	$155.67	$155.65	$155.70
Purchase #5	$184.80	6.183%	$196.2262	$196.23	$196.25	$196.20
Purchase #6	$53.64	10.158%	$59.0888	$59.09	$59.10	$59.10
Purchase #7	$233.80	5.316%	$246.2288	$246.23	$246.25	$246.20
7 purchase totals =	$1,060.76		$1,143.3277	$1,143.34	$1,143.40	$1,143.40