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	$227.45	5.852%	$240.7604	$240.76	$240.75	$240.80
Purchase #2	$62.68	3.816%	$65.0719	$65.07	$65.05	$65.10
Purchase #3	$141.73	6.401%	$150.8021	$150.80	$150.80	$150.80
Purchase #4	$72.82	7.589%	$78.3463	$78.35	$78.35	$78.30
Purchase #5	$148.51	7.676%	$159.9096	$159.91	$159.90	$159.90
Purchase #6	$221.69	3.364%	$229.1477	$229.15	$229.15	$229.10
Purchase #7	$192.93	6.478%	$205.428	$205.43	$205.45	$205.40
7 purchase totals =	$1,067.81		$1,129.4660	$1,129.47	$1,129.45	$1,129.40