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	$152.44	9.820%	$167.4096	$167.41	$167.40	$167.40
Purchase #2	$46.31	11.328%	$51.556	$51.56	$51.55	$51.60
Purchase #3	$53.25	12.403%	$59.8546	$59.85	$59.85	$59.90
Purchase #4	$84.98	5.612%	$89.7491	$89.75	$89.75	$89.70
Purchase #5	$173.52	9.471%	$189.9541	$189.95	$189.95	$190.00
Purchase #6	$225.49	9.190%	$246.2125	$246.21	$246.20	$246.20
Purchase #7	$218.69	6.312%	$232.4937	$232.49	$232.50	$232.50
7 purchase totals =	$954.68		$1,037.2296	$1,037.22	$1,037.20	$1,037.30