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	$98.96	4.489%	$103.4023	$103.40	$103.40	$103.40
Purchase #2	$223.82	8.348%	$242.5045	$242.50	$242.50	$242.50
Purchase #3	$175.92	3.692%	$182.415	$182.42	$182.40	$182.40
Purchase #4	$33.51	10.771%	$37.1194	$37.12	$37.10	$37.10
Purchase #5	$56.25	9.168%	$61.407	$61.41	$61.40	$61.40
Purchase #6	$146.85	8.193%	$158.8814	$158.88	$158.90	$158.90
Purchase #7	$101.43	7.757%	$109.2979	$109.30	$109.30	$109.30
7 purchase totals =	$836.74		$895.0275	$895.03	$895.00	$895.00