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	$182.36	7.725%	$196.4473	$196.45	$196.45	$196.40
Purchase #2	$46.61	9.237%	$50.9154	$50.92	$50.90	$50.90
Purchase #3	$62.46	7.764%	$67.3094	$67.31	$67.30	$67.30
Purchase #4	$168.37	9.135%	$183.7506	$183.75	$183.75	$183.80
Purchase #5	$160.82	6.565%	$171.3778	$171.38	$171.40	$171.40
Purchase #6	$128.71	5.220%	$135.4287	$135.43	$135.45	$135.40
Purchase #7	$157.26	9.481%	$172.1698	$172.17	$172.15	$172.20
7 purchase totals =	$906.59		$977.3990	$977.41	$977.40	$977.40