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	$171.82	13.559%	$195.1171	$195.12	$195.10	$195.10
Purchase #2	$243.97	4.252%	$254.3436	$254.34	$254.35	$254.30
Purchase #3	$130.95	6.265%	$139.154	$139.15	$139.15	$139.20
Purchase #4	$50.47	6.550%	$53.7758	$53.78	$53.80	$53.80
Purchase #5	$122.54	4.141%	$127.6144	$127.61	$127.60	$127.60
Purchase #6	$169.35	4.166%	$176.4051	$176.41	$176.40	$176.40
Purchase #7	$58.70	10.705%	$64.9838	$64.98	$65.00	$65.00
7 purchase totals =	$947.80		$1,011.3938	$1,011.39	$1,011.40	$1,011.40