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	$176.26	13.102%	$199.3536	$199.35	$199.35	$199.40
Purchase #2	$184.31	6.539%	$196.362	$196.36	$196.35	$196.40
Purchase #3	$237.78	5.304%	$250.3919	$250.39	$250.40	$250.40
Purchase #4	$38.64	6.742%	$41.2451	$41.25	$41.25	$41.20
Purchase #5	$7.41	7.701%	$7.9806	$7.98	$8.00	$8.00
Purchase #6	$130.61	7.437%	$140.3235	$140.32	$140.30	$140.30
Purchase #7	$160.28	11.719%	$179.0632	$179.06	$179.05	$179.10
7 purchase totals =	$935.29		$1,014.7199	$1,014.71	$1,014.70	$1,014.80