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	$185.56	4.810%	$194.4854	$194.49	$194.50	$194.50
Purchase #2	$73.61	6.664%	$78.5154	$78.52	$78.50	$78.50
Purchase #3	$109.83	4.107%	$114.3407	$114.34	$114.35	$114.30
Purchase #4	$165.91	9.639%	$181.9021	$181.90	$181.90	$181.90
Purchase #5	$250.53	8.362%	$271.4793	$271.48	$271.50	$271.50
Purchase #6	$148.83	13.480%	$168.8923	$168.89	$168.90	$168.90
Purchase #7	$156.87	4.492%	$163.9166	$163.92	$163.90	$163.90
7 purchase totals =	$1,091.14		$1,173.5318	$1,173.54	$1,173.55	$1,173.50