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	$179.88	8.382%	$194.9575	$194.96	$194.95	$195.00
Purchase #2	$164.29	12.108%	$184.1822	$184.18	$184.20	$184.20
Purchase #3	$77.46	6.542%	$82.5274	$82.53	$82.55	$82.50
Purchase #4	$203.72	6.240%	$216.4321	$216.43	$216.45	$216.40
Purchase #5	$146.28	6.557%	$155.8716	$155.87	$155.85	$155.90
Purchase #6	$179.69	9.445%	$196.6617	$196.66	$196.65	$196.70
Purchase #7	$53.93	10.624%	$59.6595	$59.66	$59.65	$59.70
7 purchase totals =	$1,005.25		$1,090.2920	$1,090.29	$1,090.30	$1,090.40