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	$152.67	8.352%	$165.421	$165.42	$165.40	$165.40
Purchase #2	$161.59	13.192%	$182.907	$182.91	$182.90	$182.90
Purchase #3	$175.66	8.563%	$190.7018	$190.70	$190.70	$190.70
Purchase #4	$98.78	4.824%	$103.5451	$103.55	$103.55	$103.50
Purchase #5	$195.64	8.694%	$212.6489	$212.65	$212.65	$212.60
Purchase #6	$152.32	8.337%	$165.0189	$165.02	$165.00	$165.00
Purchase #7	$153.95	7.439%	$165.4023	$165.40	$165.40	$165.40
7 purchase totals =	$1,090.61		$1,185.6450	$1,185.65	$1,185.60	$1,185.50