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	$187.90	4.561%	$196.4701	$196.47	$196.45	$196.50
Purchase #2	$66.85	11.435%	$74.4943	$74.49	$74.50	$74.50
Purchase #3	$75.46	7.497%	$81.1172	$81.12	$81.10	$81.10
Purchase #4	$55.32	8.152%	$59.8297	$59.83	$59.85	$59.80
Purchase #5	$187.33	5.366%	$197.3821	$197.38	$197.40	$197.40
Purchase #6	$230.92	7.508%	$248.2575	$248.26	$248.25	$248.30
Purchase #7	$150.37	4.781%	$157.5592	$157.56	$157.55	$157.60
7 purchase totals =	$954.15		$1,015.1101	$1,015.11	$1,015.10	$1,015.20