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	$179.25	12.681%	$201.9807	$201.98	$202.00	$202.00
Purchase #2	$95.90	4.507%	$100.2222	$100.22	$100.20	$100.20
Purchase #3	$236.33	3.819%	$245.3554	$245.36	$245.35	$245.40
Purchase #4	$100.59	4.829%	$105.4475	$105.45	$105.45	$105.40
Purchase #5	$95.27	3.122%	$98.2443	$98.24	$98.25	$98.20
Purchase #6	$229.39	13.443%	$260.2269	$260.23	$260.25	$260.20
Purchase #7	$31.46	6.558%	$33.5231	$33.52	$33.50	$33.50
7 purchase totals =	$968.19		$1,045.0001	$1,045.00	$1,045.00	$1,044.90