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	$167.35	12.347%	$188.0127	$188.01	$188.00	$188.00
Purchase #2	$118.32	8.179%	$127.9974	$128.00	$128.00	$128.00
Purchase #3	$86.32	5.302%	$90.8967	$90.90	$90.90	$90.90
Purchase #4	$202.75	11.494%	$226.0541	$226.05	$226.05	$226.10
Purchase #5	$175.43	7.367%	$188.3539	$188.35	$188.35	$188.40
Purchase #6	$69.61	5.524%	$73.4553	$73.46	$73.45	$73.50
Purchase #7	$194.27	11.486%	$216.5839	$216.58	$216.60	$216.60
7 purchase totals =	$1,014.05		$1,111.3540	$1,111.35	$1,111.35	$1,111.50