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	$135.88	7.628%	$146.2449	$146.24	$146.25	$146.20
Purchase #2	$60.46	7.266%	$64.853	$64.85	$64.85	$64.90
Purchase #3	$203.37	4.749%	$213.028	$213.03	$213.05	$213.00
Purchase #4	$145.33	3.839%	$150.9092	$150.91	$150.90	$150.90
Purchase #5	$172.66	5.273%	$181.7644	$181.76	$181.75	$181.80
Purchase #6	$174.34	8.140%	$188.5313	$188.53	$188.55	$188.50
Purchase #7	$138.49	5.742%	$146.4421	$146.44	$146.45	$146.40
7 purchase totals =	$1,030.53		$1,091.7729	$1,091.76	$1,091.80	$1,091.70