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	$174.33	12.653%	$196.388	$196.39	$196.40	$196.40
Purchase #2	$120.83	3.656%	$125.2475	$125.25	$125.25	$125.20
Purchase #3	$197.43	10.642%	$218.4405	$218.44	$218.45	$218.40
Purchase #4	$32.51	12.135%	$36.4551	$36.46	$36.45	$36.50
Purchase #5	$74.27	5.108%	$78.0637	$78.06	$78.05	$78.10
Purchase #6	$184.30	6.276%	$195.8667	$195.87	$195.85	$195.90
Purchase #7	$151.40	10.482%	$167.2697	$167.27	$167.25	$167.30
7 purchase totals =	$935.07		$1,017.7312	$1,017.74	$1,017.70	$1,017.80