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	$145.72	4.316%	$152.0093	$152.01	$152.00	$152.00
Purchase #2	$135.63	9.305%	$148.2504	$148.25	$148.25	$148.30
Purchase #3	$243.97	6.137%	$258.9424	$258.94	$258.95	$258.90
Purchase #4	$23.46	9.815%	$25.7626	$25.76	$25.75	$25.80
Purchase #5	$239.69	6.834%	$256.0704	$256.07	$256.05	$256.10
Purchase #6	$106.81	3.333%	$110.37	$110.37	$110.35	$110.40
Purchase #7	$59.26	3.800%	$61.5119	$61.51	$61.50	$61.50
7 purchase totals =	$954.54		$1,012.9170	$1,012.91	$1,012.85	$1,013.00