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	$162.98	7.137%	$174.6119	$174.61	$174.60	$174.60
Purchase #2	$50.65	9.431%	$55.4268	$55.43	$55.45	$55.40
Purchase #3	$150.63	3.719%	$156.2319	$156.23	$156.25	$156.20
Purchase #4	$112.31	7.462%	$120.6906	$120.69	$120.70	$120.70
Purchase #5	$175.73	11.518%	$195.9706	$195.97	$195.95	$196.00
Purchase #6	$82.61	9.549%	$90.4984	$90.50	$90.50	$90.50
Purchase #7	$226.79	7.766%	$244.4025	$244.40	$244.40	$244.40
7 purchase totals =	$961.70		$1,037.8327	$1,037.83	$1,037.85	$1,037.80